### 导航 - [索引](../genindex.xhtml "总目录") - [模块](../py-modindex.xhtml "Python 模块索引") | - [下一页](3.5.xhtml "Python 3.5 有什么新变化") | - [上一页](3.7.xhtml "Python 3.7 有什么新变化") | -  - [Python](https://www.python.org/) » - zh\_CN 3.7.3 [文档](../index.xhtml) » - [Python 有什么新变化？](index.xhtml) » - $('.inline-search').show(0); | # Python 3.6 有什么新变化A 作者Elvis Pranskevichus <[elvis@magic.io](mailto:elvis%40magic.io)>, Yury Selivanov <[yury@magic.io](mailto:yury%40magic.io)> 本文解释了与3.5相比，Python 3.6中的新功能。 Python 3.6于2016年12月23日发布。请参阅 [changelog](https://docs.python.org/3.6/whatsnew/changelog.html) \[https://docs.python.org/3.6/whatsnew/changelog.html\] 以获取完整的更改列表。 参见 [**PEP 494**](https://www.python.org/dev/peps/pep-0494) \[https://www.python.org/dev/peps/pep-0494\] - Python 3.6发布计划 ## 摘要 - 发布重点 新的语法特性： - [PEP 498](#whatsnew36-pep498), 格式化的字符串文字 - [PEP 515](#whatsnew36-pep515), 数字文字中的下划线。 - [PEP 526](#whatsnew36-pep526) , 变量注释的语法。 - [PEP 525](#whatsnew36-pep525), 异步生成器。 - [PEP 530](#whatsnew36-pep530): 异步推导。 新的库模块： - [`secrets`](../library/secrets.xhtml#module-secrets "secrets: Generate secure random numbers for managing secrets."): [PEP 506 -- Adding A Secrets Module To The Standard Library](#whatsnew36-pep506). CPython 实现的改进： - The [dict](../library/stdtypes.xhtml#typesmapping) type has been reimplemented to use a [more compact representation](#whatsnew36-compactdict)based on [a proposal by Raymond Hettinger](https://mail.python.org/pipermail/python-dev/2012-December/123028.html) \[https://mail.python.org/pipermail/python-dev/2012-December/123028.html\]and similar to the [PyPy dict implementation](https://morepypy.blogspot.com/2015/01/faster-more-memory-efficient-and-more.html) \[https://morepypy.blogspot.com/2015/01/faster-more-memory-efficient-and-more.html\]. This resulted in dictionaries using 20% to 25% less memory when compared to Python 3.5. - Customization of class creation has been simplified with the [new protocol](#whatsnew36-pep487). - The class attribute definition order is [now preserved](#whatsnew36-pep520). - The order of elements in `**kwargs` now [corresponds to the order](#whatsnew36-pep468) in which keyword arguments were passed to the function. - DTrace and SystemTap [probing support](#whatsnew36-tracing) has been added. - The new [PYTHONMALLOC](#whatsnew36-pythonmalloc) environment variable can now be used to debug the interpreter memory allocation and access errors. 标准库中的重大改进： - The [`asyncio`](../library/asyncio.xhtml#module-asyncio "asyncio: Asynchronous I/O.") module has received new features, significant usability and performance improvements, and a fair amount of bug fixes. Starting with Python 3.6 the `asyncio` module is no longer provisional and its API is considered stable. - A new [file system path protocol](#whatsnew36-pep519) has been implemented to support [path-like objects](../glossary.xhtml#term-path-like-object). All standard library functions operating on paths have been updated to work with the new protocol. - The [`datetime`](../library/datetime.xhtml#module-datetime "datetime: Basic date and time types.") module has gained support for [Local Time Disambiguation](#whatsnew36-pep495). - The [`typing`](../library/typing.xhtml#module-typing "typing: Support for type hints (see PEP 484).") module received a number of [improvements](#whatsnew36-typing). - The [`tracemalloc`](../library/tracemalloc.xhtml#module-tracemalloc "tracemalloc: Trace memory allocations.") module has been significantly reworked and is now used to provide better output for [`ResourceWarning`](../library/exceptions.xhtml#ResourceWarning "ResourceWarning")as well as provide better diagnostics for memory allocation errors. See the [PYTHONMALLOC section](#whatsnew36-pythonmalloc) for more information. 安全改进： - The new [`secrets`](../library/secrets.xhtml#module-secrets "secrets: Generate secure random numbers for managing secrets.") module has been added to simplify the generation of cryptographically strong pseudo-random numbers suitable for managing secrets such as account authentication, tokens, and similar. - On Linux, [`os.urandom()`](../library/os.xhtml#os.urandom "os.urandom") now blocks until the system urandom entropy pool is initialized to increase the security. See the [**PEP 524**](https://www.python.org/dev/peps/pep-0524) \[https://www.python.org/dev/peps/pep-0524\] for the rationale. - The [`hashlib`](../library/hashlib.xhtml#module-hashlib "hashlib: Secure hash and message digest algorithms.") and [`ssl`](../library/ssl.xhtml#module-ssl "ssl: TLS/SSL wrapper for socket objects") modules now support OpenSSL 1.1.0. - The default settings and feature set of the [`ssl`](../library/ssl.xhtml#module-ssl "ssl: TLS/SSL wrapper for socket objects") module have been improved. - The [`hashlib`](../library/hashlib.xhtml#module-hashlib "hashlib: Secure hash and message digest algorithms.") module received support for the BLAKE2, SHA-3 and SHAKE hash algorithms and the [`scrypt()`](../library/hashlib.xhtml#hashlib.scrypt "hashlib.scrypt") key derivation function. Windows改进： - [PEP 528](#whatsnew36-pep528) and [PEP 529](#whatsnew36-pep529), Windows filesystem and console encoding changed to UTF-8. - The `py.exe` launcher, when used interactively, no longer prefers Python 2 over Python 3 when the user doesn't specify a version (via command line arguments or a config file). Handling of shebang lines remains unchanged - "python" refers to Python 2 in that case. - `python.exe` and `pythonw.exe` have been marked as long-path aware, which means that the 260 character path limit may no longer apply. See [removing the MAX\_PATH limitation](../using/windows.xhtml#max-path) for details. - A `._pth` file can be added to force isolated mode and fully specify all search paths to avoid registry and environment lookup. See [the documentation](../using/windows.xhtml#finding-modules) for more information. - A `python36.zip` file now works as a landmark to infer [`PYTHONHOME`](../using/cmdline.xhtml#envvar-PYTHONHOME). See [the documentation](../using/windows.xhtml#finding-modules) for more information. ## 新的特性 ### PEP 498: 格式化的字符串文字 [**PEP 498**](https://www.python.org/dev/peps/pep-0498) \[https://www.python.org/dev/peps/pep-0498\] introduces a new kind of string literals: *f-strings*, or [formatted string literals](../reference/lexical_analysis.xhtml#f-strings). Formatted string literals are prefixed with `'f'` and are similar to the format strings accepted by [`str.format()`](../library/stdtypes.xhtml#str.format "str.format"). They contain replacement fields surrounded by curly braces. The replacement fields are expressions, which are evaluated at run time, and then formatted using the [`format()`](../library/functions.xhtml#format "format") protocol: ``` >>> name = "Fred" >>> f"He said his name is {name}." 'He said his name is Fred.' >>> width = 10 >>> precision = 4 >>> value = decimal.Decimal("12.34567") >>> f"result: {value:{width}.{precision}}" # nested fields 'result: 12.35' ``` 参见 [**PEP 498**](https://www.python.org/dev/peps/pep-0498) \[https://www.python.org/dev/peps/pep-0498\] -- 文字字符串插值。PEP 由 Eric V. Smith 撰写并实现 [Feature documentation](../reference/lexical_analysis.xhtml#f-strings). ### PEP 526: 变量注释的语法 [**PEP 484**](https://www.python.org/dev/peps/pep-0484) \[https://www.python.org/dev/peps/pep-0484\] introduced the standard for type annotations of function parameters, a.k.a. type hints. This PEP adds syntax to Python for annotating the types of variables including class variables and instance variables: ``` primes: List[int] = [] captain: str # Note: no initial value! class Starship: stats: Dict[str, int] = {} ``` Just as for function annotations, the Python interpreter does not attach any particular meaning to variable annotations and only stores them in the `__annotations__` attribute of a class or module. In contrast to variable declarations in statically typed languages, the goal of annotation syntax is to provide an easy way to specify structured type metadata for third party tools and libraries via the abstract syntax tree and the `__annotations__` attribute. 参见 [**PEP 526**](https://www.python.org/dev/peps/pep-0526) \[https://www.python.org/dev/peps/pep-0526\] -- 变量注释的语法。PEP written by Ryan Gonzalez, Philip House, Ivan Levkivskyi, Lisa Roach, and Guido van Rossum. Implemented by Ivan Levkivskyi. Tools that use or will use the new syntax: [mypy](http://www.mypy-lang.org/) \[http://www.mypy-lang.org/\], [pytype](https://github.com/google/pytype) \[https://github.com/google/pytype\], PyCharm, etc. ### PEP 515: 数字文字中的下划线。 [**PEP 515**](https://www.python.org/dev/peps/pep-0515) \[https://www.python.org/dev/peps/pep-0515\] adds the ability to use underscores in numeric literals for improved readability. For example: ``` >>> 1_000_000_000_000_000 1000000000000000 >>> 0x_FF_FF_FF_FF 4294967295 ``` Single underscores are allowed between digits and after any base specifier. Leading, trailing, or multiple underscores in a row are not allowed. The [string formatting](../library/string.xhtml#formatspec) language also now has support for the `'_'` option to signal the use of an underscore for a thousands separator for floating point presentation types and for integer presentation type `'d'`. For integer presentation types `'b'`, `'o'`, `'x'`, and `'X'`, underscores will be inserted every 4 digits: ``` >>> '{:_}'.format(1000000) '1_000_000' >>> '{:_x}'.format(0xFFFFFFFF) 'ffff_ffff' ``` 参见 [**PEP 515**](https://www.python.org/dev/peps/pep-0515) \[https://www.python.org/dev/peps/pep-0515\] -- 数字文字中的下划线。PEP 由 Georg Brandl 和 Serhiy Storchaka 撰写 ### PEP 525: 异步生成器 [**PEP 492**](https://www.python.org/dev/peps/pep-0492) \[https://www.python.org/dev/peps/pep-0492\] introduced support for native coroutines and `async` / `await`syntax to Python 3.5. A notable limitation of the Python 3.5 implementation is that it was not possible to use `await` and `yield` in the same function body. In Python 3.6 this restriction has been lifted, making it possible to define *asynchronous generators*: ``` async def ticker(delay, to): """Yield numbers from 0 to *to* every *delay* seconds.""" for i in range(to): yield i await asyncio.sleep(delay) ``` The new syntax allows for faster and more concise code. 参见 [**PEP 525**](https://www.python.org/dev/peps/pep-0525) \[https://www.python.org/dev/peps/pep-0525\] -- 异步生成器PEP 由 Yury Selivanov 撰写并实现 ### PEP 530: Asynchronous Comprehensions [**PEP 530**](https://www.python.org/dev/peps/pep-0530) \[https://www.python.org/dev/peps/pep-0530\] adds support for using `async for` in list, set, dict comprehensions and generator expressions: ``` result = [i async for i in aiter() if i % 2] ``` Additionally, `await` expressions are supported in all kinds of comprehensions: ``` result = [await fun() for fun in funcs if await condition()] ``` 参见 [**PEP 530**](https://www.python.org/dev/peps/pep-0530) \[https://www.python.org/dev/peps/pep-0530\] -- Asynchronous ComprehensionsPEP 由 Yury Selivanov 撰写并实现 ### PEP 487: Simpler customization of class creation It is now possible to customize subclass creation without using a metaclass. The new `__init_subclass__` classmethod will be called on the base class whenever a new subclass is created: ``` class PluginBase: subclasses = [] def __init_subclass__(cls, **kwargs): super().__init_subclass__(**kwargs) cls.subclasses.append(cls) class Plugin1(PluginBase): pass class Plugin2(PluginBase): pass ``` In order to allow zero-argument [`super()`](../library/functions.xhtml#super "super") calls to work correctly from [`__init_subclass__()`](../reference/datamodel.xhtml#object.__init_subclass__ "object.__init_subclass__") implementations, custom metaclasses must ensure that the new `__classcell__` namespace entry is propagated to `type.__new__` (as described in [创建类对象](../reference/datamodel.xhtml#class-object-creation)). 参见 [**PEP 487**](https://www.python.org/dev/peps/pep-0487) \[https://www.python.org/dev/peps/pep-0487\] -- Simpler customization of class creationPEP 由 Martin Teichmann 撰写并实现。 [Feature documentation](../reference/datamodel.xhtml#class-customization) ### PEP 487: Descriptor Protocol Enhancements [**PEP 487**](https://www.python.org/dev/peps/pep-0487) \[https://www.python.org/dev/peps/pep-0487\] extends the descriptor protocol to include the new optional [`__set_name__()`](../reference/datamodel.xhtml#object.__set_name__ "object.__set_name__") method. Whenever a new class is defined, the new method will be called on all descriptors included in the definition, providing them with a reference to the class being defined and the name given to the descriptor within the class namespace. In other words, instances of descriptors can now know the attribute name of the descriptor in the owner class: ``` class IntField: def __get__(self, instance, owner): return instance.__dict__[self.name] def __set__(self, instance, value): if not isinstance(value, int): raise ValueError(f'expecting integer in {self.name}') instance.__dict__[self.name] = value # this is the new initializer: def __set_name__(self, owner, name): self.name = name class Model: int_field = IntField() ``` 参见 [**PEP 487**](https://www.python.org/dev/peps/pep-0487) \[https://www.python.org/dev/peps/pep-0487\] -- Simpler customization of class creationPEP 由 Martin Teichmann 撰写并实现。 [Feature documentation](../reference/datamodel.xhtml#descriptors) ### PEP 519: Adding a file system path protocol File system paths have historically been represented as [`str`](../library/stdtypes.xhtml#str "str")or [`bytes`](../library/stdtypes.xhtml#bytes "bytes") objects. This has led to people who write code which operate on file system paths to assume that such objects are only one of those two types (an [`int`](../library/functions.xhtml#int "int") representing a file descriptor does not count as that is not a file path). Unfortunately that assumption prevents alternative object representations of file system paths like [`pathlib`](../library/pathlib.xhtml#module-pathlib "pathlib: Object-oriented filesystem paths") from working with pre-existing code, including Python's standard library. To fix this situation, a new interface represented by [`os.PathLike`](../library/os.xhtml#os.PathLike "os.PathLike") has been defined. By implementing the [`__fspath__()`](../library/os.xhtml#os.PathLike.__fspath__ "os.PathLike.__fspath__") method, an object signals that it represents a path. An object can then provide a low-level representation of a file system path as a [`str`](../library/stdtypes.xhtml#str "str") or [`bytes`](../library/stdtypes.xhtml#bytes "bytes") object. This means an object is considered [path-like](../glossary.xhtml#term-path-like-object) if it implements [`os.PathLike`](../library/os.xhtml#os.PathLike "os.PathLike") or is a [`str`](../library/stdtypes.xhtml#str "str") or [`bytes`](../library/stdtypes.xhtml#bytes "bytes") object which represents a file system path. Code can use [`os.fspath()`](../library/os.xhtml#os.fspath "os.fspath"), [`os.fsdecode()`](../library/os.xhtml#os.fsdecode "os.fsdecode"), or [`os.fsencode()`](../library/os.xhtml#os.fsencode "os.fsencode") to explicitly get a [`str`](../library/stdtypes.xhtml#str "str") and/or [`bytes`](../library/stdtypes.xhtml#bytes "bytes") representation of a path-like object. The built-in [`open()`](../library/functions.xhtml#open "open") function has been updated to accept [`os.PathLike`](../library/os.xhtml#os.PathLike "os.PathLike") objects, as have all relevant functions in the [`os`](../library/os.xhtml#module-os "os: Miscellaneous operating system interfaces.") and [`os.path`](../library/os.path.xhtml#module-os.path "os.path: Operations on pathnames.") modules, and most other functions and classes in the standard library. The [`os.DirEntry`](../library/os.xhtml#os.DirEntry "os.DirEntry") class and relevant classes in [`pathlib`](../library/pathlib.xhtml#module-pathlib "pathlib: Object-oriented filesystem paths") have also been updated to implement [`os.PathLike`](../library/os.xhtml#os.PathLike "os.PathLike"). The hope is that updating the fundamental functions for operating on file system paths will lead to third-party code to implicitly support all [path-like objects](../glossary.xhtml#term-path-like-object) without any code changes, or at least very minimal ones (e.g. calling [`os.fspath()`](../library/os.xhtml#os.fspath "os.fspath") at the beginning of code before operating on a path-like object). Here are some examples of how the new interface allows for [`pathlib.Path`](../library/pathlib.xhtml#pathlib.Path "pathlib.Path") to be used more easily and transparently with pre-existing code: ``` >>> import pathlib >>> with open(pathlib.Path("README")) as f: ... contents = f.read() ... >>> import os.path >>> os.path.splitext(pathlib.Path("some_file.txt")) ('some_file', '.txt') >>> os.path.join("/a/b", pathlib.Path("c")) '/a/b/c' >>> import os >>> os.fspath(pathlib.Path("some_file.txt")) 'some_file.txt' ``` (Implemented by Brett Cannon, Ethan Furman, Dusty Phillips, and Jelle Zijlstra.) 参见 [**PEP 519**](https://www.python.org/dev/peps/pep-0519) \[https://www.python.org/dev/peps/pep-0519\] -- Adding a file system path protocolPEP written by Brett Cannon and Koos Zevenhoven. ### PEP 495: Local Time Disambiguation In most world locations, there have been and will be times when local clocks are moved back. In those times, intervals are introduced in which local clocks show the same time twice in the same day. In these situations, the information displayed on a local clock (or stored in a Python datetime instance) is insufficient to identify a particular moment in time. [**PEP 495**](https://www.python.org/dev/peps/pep-0495) \[https://www.python.org/dev/peps/pep-0495\] adds the new *fold* attribute to instances of [`datetime.datetime`](../library/datetime.xhtml#datetime.datetime "datetime.datetime") and [`datetime.time`](../library/datetime.xhtml#datetime.time "datetime.time") classes to differentiate between two moments in time for which local times are the same: ``` >>> u0 = datetime(2016, 11, 6, 4, tzinfo=timezone.utc) >>> for i in range(4): ... u = u0 + i*HOUR ... t = u.astimezone(Eastern) ... print(u.time(), 'UTC =', t.time(), t.tzname(), t.fold) ... 04:00:00 UTC = 00:00:00 EDT 0 05:00:00 UTC = 01:00:00 EDT 0 06:00:00 UTC = 01:00:00 EST 1 07:00:00 UTC = 02:00:00 EST 0 ``` The values of the [`fold`](../library/datetime.xhtml#datetime.datetime.fold "datetime.datetime.fold") attribute have the value `0` for all instances except those that represent the second (chronologically) moment in time in an ambiguous case. 参见 [**PEP 495**](https://www.python.org/dev/peps/pep-0495) \[https://www.python.org/dev/peps/pep-0495\] -- Local Time DisambiguationPEP written by Alexander Belopolsky and Tim Peters, implementation by Alexander Belopolsky. ### PEP 529: Change Windows filesystem encoding to UTF-8 Representing filesystem paths is best performed with str (Unicode) rather than bytes. However, there are some situations where using bytes is sufficient and correct. Prior to Python 3.6, data loss could result when using bytes paths on Windows. With this change, using bytes to represent paths is now supported on Windows, provided those bytes are encoded with the encoding returned by [`sys.getfilesystemencoding()`](../library/sys.xhtml#sys.getfilesystemencoding "sys.getfilesystemencoding"), which now defaults to `'utf-8'`. Applications that do not use str to represent paths should use [`os.fsencode()`](../library/os.xhtml#os.fsencode "os.fsencode") and [`os.fsdecode()`](../library/os.xhtml#os.fsdecode "os.fsdecode") to ensure their bytes are correctly encoded. To revert to the previous behaviour, set [`PYTHONLEGACYWINDOWSFSENCODING`](../using/cmdline.xhtml#envvar-PYTHONLEGACYWINDOWSFSENCODING) or call [`sys._enablelegacywindowsfsencoding()`](../library/sys.xhtml#sys._enablelegacywindowsfsencoding "sys._enablelegacywindowsfsencoding"). See [**PEP 529**](https://www.python.org/dev/peps/pep-0529) \[https://www.python.org/dev/peps/pep-0529\] for more information and discussion of code modifications that may be required. ### PEP 528: Change Windows console encoding to UTF-8 The default console on Windows will now accept all Unicode characters and provide correctly read str objects to Python code. `sys.stdin`, `sys.stdout` and `sys.stderr` now default to utf-8 encoding. This change only applies when using an interactive console, and not when redirecting files or pipes. To revert to the previous behaviour for interactive console use, set [`PYTHONLEGACYWINDOWSSTDIO`](../using/cmdline.xhtml#envvar-PYTHONLEGACYWINDOWSSTDIO). 参见 [**PEP 528**](https://www.python.org/dev/peps/pep-0528) \[https://www.python.org/dev/peps/pep-0528\] -- Change Windows console encoding to UTF-8PEP written and implemented by Steve Dower. ### PEP 520: Preserving Class Attribute Definition Order Attributes in a class definition body have a natural ordering: the same order in which the names appear in the source. This order is now preserved in the new class's [`__dict__`](../library/stdtypes.xhtml#object.__dict__ "object.__dict__") attribute. Also, the effective default class *execution* namespace (returned from [type.\_\_prepare\_\_()](../reference/datamodel.xhtml#prepare)) is now an insertion-order-preserving mapping. 参见 [**PEP 520**](https://www.python.org/dev/peps/pep-0520) \[https://www.python.org/dev/peps/pep-0520\] -- Preserving Class Attribute Definition OrderPEP written and implemented by Eric Snow. ### PEP 468: Preserving Keyword Argument Order `**kwargs` in a function signature is now guaranteed to be an insertion-order-preserving mapping. 参见 [**PEP 468**](https://www.python.org/dev/peps/pep-0468) \[https://www.python.org/dev/peps/pep-0468\] -- Preserving Keyword Argument OrderPEP written and implemented by Eric Snow. ### New [dict](../library/stdtypes.xhtml#typesmapping) implementation The [dict](../library/stdtypes.xhtml#typesmapping) type now uses a "compact" representation based on [a proposal by Raymond Hettinger](https://mail.python.org/pipermail/python-dev/2012-December/123028.html) \[https://mail.python.org/pipermail/python-dev/2012-December/123028.html\]which was [first implemented by PyPy](https://morepypy.blogspot.com/2015/01/faster-more-memory-efficient-and-more.html) \[https://morepypy.blogspot.com/2015/01/faster-more-memory-efficient-and-more.html\]. The memory usage of the new [`dict()`](../library/stdtypes.xhtml#dict "dict") is between 20% and 25% smaller compared to Python 3.5. The order-preserving aspect of this new implementation is considered an implementation detail and should not be relied upon (this may change in the future, but it is desired to have this new dict implementation in the language for a few releases before changing the language spec to mandate order-preserving semantics for all current and future Python implementations; this also helps preserve backwards-compatibility with older versions of the language where random iteration order is still in effect, e.g. Python 3.5). (Contributed by INADA Naoki in [bpo-27350](https://bugs.python.org/issue27350) \[https://bugs.python.org/issue27350\]. Idea [originally suggested by Raymond Hettinger](https://mail.python.org/pipermail/python-dev/2012-December/123028.html) \[https://mail.python.org/pipermail/python-dev/2012-December/123028.html\].) ### PEP 523: Adding a frame evaluation API to CPython While Python provides extensive support to customize how code executes, one place it has not done so is in the evaluation of frame objects. If you wanted some way to intercept frame evaluation in Python there really wasn't any way without directly manipulating function pointers for defined functions. [**PEP 523**](https://www.python.org/dev/peps/pep-0523) \[https://www.python.org/dev/peps/pep-0523\] changes this by providing an API to make frame evaluation pluggable at the C level. This will allow for tools such as debuggers and JITs to intercept frame evaluation before the execution of Python code begins. This enables the use of alternative evaluation implementations for Python code, tracking frame evaluation, etc. This API is not part of the limited C API and is marked as private to signal that usage of this API is expected to be limited and only applicable to very select, low-level use-cases. Semantics of the API will change with Python as necessary. 参见 [**PEP 523**](https://www.python.org/dev/peps/pep-0523) \[https://www.python.org/dev/peps/pep-0523\] -- Adding a frame evaluation API to CPythonPEP written by Brett Cannon and Dino Viehland. ### PYTHONMALLOC environment variable The new [`PYTHONMALLOC`](../using/cmdline.xhtml#envvar-PYTHONMALLOC) environment variable allows setting the Python memory allocators and installing debug hooks. It is now possible to install debug hooks on Python memory allocators on Python compiled in release mode using `PYTHONMALLOC=debug`. Effects of debug hooks: - Newly allocated memory is filled with the byte `0xCB` - Freed memory is filled with the byte `0xDB` - Detect violations of the Python memory allocator API. For example, [`PyObject_Free()`](../c-api/memory.xhtml#c.PyObject_Free "PyObject_Free") called on a memory block allocated by [`PyMem_Malloc()`](../c-api/memory.xhtml#c.PyMem_Malloc "PyMem_Malloc"). - Detect writes before the start of a buffer (buffer underflows) - Detect writes after the end of a buffer (buffer overflows) - Check that the [GIL](../glossary.xhtml#term-global-interpreter-lock) is held when allocator functions of [`PYMEM_DOMAIN_OBJ`](../c-api/memory.xhtml#c.PYMEM_DOMAIN_OBJ "PYMEM_DOMAIN_OBJ") (ex: [`PyObject_Malloc()`](../c-api/memory.xhtml#c.PyObject_Malloc "PyObject_Malloc")) and [`PYMEM_DOMAIN_MEM`](../c-api/memory.xhtml#c.PYMEM_DOMAIN_MEM "PYMEM_DOMAIN_MEM") (ex: [`PyMem_Malloc()`](../c-api/memory.xhtml#c.PyMem_Malloc "PyMem_Malloc")) domains are called. Checking if the GIL is held is also a new feature of Python 3.6. See the [`PyMem_SetupDebugHooks()`](../c-api/memory.xhtml#c.PyMem_SetupDebugHooks "PyMem_SetupDebugHooks") function for debug hooks on Python memory allocators. It is now also possible to force the usage of the `malloc()` allocator of the C library for all Python memory allocations using `PYTHONMALLOC=malloc`. This is helpful when using external memory debuggers like Valgrind on a Python compiled in release mode. On error, the debug hooks on Python memory allocators now use the [`tracemalloc`](../library/tracemalloc.xhtml#module-tracemalloc "tracemalloc: Trace memory allocations.") module to get the traceback where a memory block was allocated. Example of fatal error on buffer overflow using `python3.6 -X tracemalloc=5` (store 5 frames in traces): ``` Debug memory block at address p=0x7fbcd41666f8: API 'o' 4 bytes originally requested The 7 pad bytes at p-7 are FORBIDDENBYTE, as expected. The 8 pad bytes at tail=0x7fbcd41666fc are not all FORBIDDENBYTE (0xfb): at tail+0: 0x02 *** OUCH at tail+1: 0xfb at tail+2: 0xfb at tail+3: 0xfb at tail+4: 0xfb at tail+5: 0xfb at tail+6: 0xfb at tail+7: 0xfb The block was made by call #1233329 to debug malloc/realloc. Data at p: 1a 2b 30 00 Memory block allocated at (most recent call first): File "test/test_bytes.py", line 323 File "unittest/case.py", line 600 File "unittest/case.py", line 648 File "unittest/suite.py", line 122 File "unittest/suite.py", line 84 Fatal Python error: bad trailing pad byte Current thread 0x00007fbcdbd32700 (most recent call first): File "test/test_bytes.py", line 323 in test_hex File "unittest/case.py", line 600 in run File "unittest/case.py", line 648 in __call__ File "unittest/suite.py", line 122 in run File "unittest/suite.py", line 84 in __call__ File "unittest/suite.py", line 122 in run File "unittest/suite.py", line 84 in __call__ ... ``` (Contributed by Victor Stinner in [bpo-26516](https://bugs.python.org/issue26516) \[https://bugs.python.org/issue26516\] and [bpo-26564](https://bugs.python.org/issue26564) \[https://bugs.python.org/issue26564\].) ### DTrace and SystemTap probing support Python can now be built `--with-dtrace` which enables static markers for the following events in the interpreter: - function call/return - garbage collection started/finished - 执行的代码行。 This can be used to instrument running interpreters in production, without the need to recompile specific debug builds or providing application-specific profiling/debugging code. More details in [使用 DTrace 和 SystemTap 检测CPython](../howto/instrumentation.xhtml#instrumentation). The current implementation is tested on Linux and macOS. Additional markers may be added in the future. (Contributed by Łukasz Langa in [bpo-21590](https://bugs.python.org/issue21590) \[https://bugs.python.org/issue21590\], based on patches by Jesús Cea Avión, David Malcolm, and Nikhil Benesch.) ## 其他语言特性修改 Some smaller changes made to the core Python language are: - A `global` or `nonlocal` statement must now textually appear before the first use of the affected name in the same scope. Previously this was a [`SyntaxWarning`](../library/exceptions.xhtml#SyntaxWarning "SyntaxWarning"). - It is now possible to set a [special method](../reference/datamodel.xhtml#specialnames) to `None` to indicate that the corresponding operation is not available. For example, if a class sets [`__iter__()`](../reference/datamodel.xhtml#object.__iter__ "object.__iter__") to `None`, the class is not iterable. (Contributed by Andrew Barnert and Ivan Levkivskyi in [bpo-25958](https://bugs.python.org/issue25958) \[https://bugs.python.org/issue25958\].) - Long sequences of repeated traceback lines are now abbreviated as `"[Previous line repeated {count} more times]"` (see [traceback](#whatsnew36-traceback) for an example). (Contributed by Emanuel Barry in [bpo-26823](https://bugs.python.org/issue26823) \[https://bugs.python.org/issue26823\].) - Import now raises the new exception [`ModuleNotFoundError`](../library/exceptions.xhtml#ModuleNotFoundError "ModuleNotFoundError")(subclass of [`ImportError`](../library/exceptions.xhtml#ImportError "ImportError")) when it cannot find a module. Code that currently checks for ImportError (in try-except) will still work. (Contributed by Eric Snow in [bpo-15767](https://bugs.python.org/issue15767) \[https://bugs.python.org/issue15767\].) - Class methods relying on zero-argument `super()` will now work correctly when called from metaclass methods during class creation. (Contributed by Martin Teichmann in [bpo-23722](https://bugs.python.org/issue23722) \[https://bugs.python.org/issue23722\].) ## 新增模块 ### secrets The main purpose of the new [`secrets`](../library/secrets.xhtml#module-secrets "secrets: Generate secure random numbers for managing secrets.") module is to provide an obvious way to reliably generate cryptographically strong pseudo-random values suitable for managing secrets, such as account authentication, tokens, and similar. 警告 Note that the pseudo-random generators in the [`random`](../library/random.xhtml#module-random "random: Generate pseudo-random numbers with various common distributions.") module should *NOT* be used for security purposes. Use [`secrets`](../library/secrets.xhtml#module-secrets "secrets: Generate secure random numbers for managing secrets.")on Python 3.6+ and [`os.urandom()`](../library/os.xhtml#os.urandom "os.urandom") on Python 3.5 and earlier. 参见 [**PEP 506**](https://www.python.org/dev/peps/pep-0506) \[https://www.python.org/dev/peps/pep-0506\] -- Adding A Secrets Module To The Standard LibraryPEP written and implemented by Steven D'Aprano. ## 改进的模块 ### array Exhausted iterators of [`array.array`](../library/array.xhtml#array.array "array.array") will now stay exhausted even if the iterated array is extended. This is consistent with the behavior of other mutable sequences. Contributed by Serhiy Storchaka in [bpo-26492](https://bugs.python.org/issue26492) \[https://bugs.python.org/issue26492\]. ### ast The new `ast.Constant` AST node has been added. It can be used by external AST optimizers for the purposes of constant folding. Contributed by Victor Stinner in [bpo-26146](https://bugs.python.org/issue26146) \[https://bugs.python.org/issue26146\]. ### asyncio Starting with Python 3.6 the `asyncio` module is no longer provisional and its API is considered stable. Notable changes in the [`asyncio`](../library/asyncio.xhtml#module-asyncio "asyncio: Asynchronous I/O.") module since Python 3.5.0 (all backported to 3.5.x due to the provisional status): - The [`get_event_loop()`](../library/asyncio-eventloop.xhtml#asyncio.get_event_loop "asyncio.get_event_loop") function has been changed to always return the currently running loop when called from coroutines and callbacks. (Contributed by Yury Selivanov in [bpo-28613](https://bugs.python.org/issue28613) \[https://bugs.python.org/issue28613\].) - The [`ensure_future()`](../library/asyncio-future.xhtml#asyncio.ensure_future "asyncio.ensure_future") function and all functions that use it, such as [`loop.run_until_complete()`](../library/asyncio-eventloop.xhtml#asyncio.loop.run_until_complete "asyncio.loop.run_until_complete"), now accept all kinds of [awaitable objects](../glossary.xhtml#term-awaitable). (Contributed by Yury Selivanov.) - New [`run_coroutine_threadsafe()`](../library/asyncio-task.xhtml#asyncio.run_coroutine_threadsafe "asyncio.run_coroutine_threadsafe") function to submit coroutines to event loops from other threads. (Contributed by Vincent Michel.) - New [`Transport.is_closing()`](../library/asyncio-protocol.xhtml#asyncio.BaseTransport.is_closing "asyncio.BaseTransport.is_closing")method to check if the transport is closing or closed. (Contributed by Yury Selivanov.) - The [`loop.create_server()`](../library/asyncio-eventloop.xhtml#asyncio.loop.create_server "asyncio.loop.create_server")method can now accept a list of hosts. (Contributed by Yann Sionneau.) - New [`loop.create_future()`](../library/asyncio-eventloop.xhtml#asyncio.loop.create_future "asyncio.loop.create_future")method to create Future objects. This allows alternative event loop implementations, such as [uvloop](https://github.com/MagicStack/uvloop) \[https://github.com/MagicStack/uvloop\], to provide a faster [`asyncio.Future`](../library/asyncio-future.xhtml#asyncio.Future "asyncio.Future") implementation. (Contributed by Yury Selivanov in [bpo-27041](https://bugs.python.org/issue27041) \[https://bugs.python.org/issue27041\].) - New [`loop.get_exception_handler()`](../library/asyncio-eventloop.xhtml#asyncio.loop.get_exception_handler "asyncio.loop.get_exception_handler")method to get the current exception handler. (Contributed by Yury Selivanov in [bpo-27040](https://bugs.python.org/issue27040) \[https://bugs.python.org/issue27040\].) - New [`StreamReader.readuntil()`](../library/asyncio-stream.xhtml#asyncio.StreamReader.readuntil "asyncio.StreamReader.readuntil")method to read data from the stream until a separator bytes sequence appears. (Contributed by Mark Korenberg.) - The performance of [`StreamReader.readexactly()`](../library/asyncio-stream.xhtml#asyncio.StreamReader.readexactly "asyncio.StreamReader.readexactly")has been improved. (Contributed by Mark Korenberg in [bpo-28370](https://bugs.python.org/issue28370) \[https://bugs.python.org/issue28370\].) - The [`loop.getaddrinfo()`](../library/asyncio-eventloop.xhtml#asyncio.loop.getaddrinfo "asyncio.loop.getaddrinfo")method is optimized to avoid calling the system `getaddrinfo`function if the address is already resolved. (Contributed by A. Jesse Jiryu Davis.) - The [`loop.stop()`](../library/asyncio-eventloop.xhtml#asyncio.loop.stop "asyncio.loop.stop")method has been changed to stop the loop immediately after the current iteration. Any new callbacks scheduled as a result of the last iteration will be discarded. (Contributed by Guido van Rossum in [bpo-25593](https://bugs.python.org/issue25593) \[https://bugs.python.org/issue25593\].) - `Future.set_exception`will now raise [`TypeError`](../library/exceptions.xhtml#TypeError "TypeError") when passed an instance of the [`StopIteration`](../library/exceptions.xhtml#StopIteration "StopIteration") exception. (Contributed by Chris Angelico in [bpo-26221](https://bugs.python.org/issue26221) \[https://bugs.python.org/issue26221\].) - New [`loop.connect_accepted_socket()`](../library/asyncio-eventloop.xhtml#asyncio.loop.connect_accepted_socket "asyncio.loop.connect_accepted_socket")method to be used by servers that accept connections outside of asyncio, but that use asyncio to handle them. (Contributed by Jim Fulton in [bpo-27392](https://bugs.python.org/issue27392) \[https://bugs.python.org/issue27392\].) - `TCP_NODELAY` flag is now set for all TCP transports by default. (Contributed by Yury Selivanov in [bpo-27456](https://bugs.python.org/issue27456) \[https://bugs.python.org/issue27456\].) - New [`loop.shutdown_asyncgens()`](../library/asyncio-eventloop.xhtml#asyncio.loop.shutdown_asyncgens "asyncio.loop.shutdown_asyncgens")to properly close pending asynchronous generators before closing the loop. (Contributed by Yury Selivanov in [bpo-28003](https://bugs.python.org/issue28003) \[https://bugs.python.org/issue28003\].) - [`Future`](../library/asyncio-future.xhtml#asyncio.Future "asyncio.Future") and [`Task`](../library/asyncio-task.xhtml#asyncio.Task "asyncio.Task")classes now have an optimized C implementation which makes asyncio code up to 30% faster. (Contributed by Yury Selivanov and INADA Naoki in [bpo-26081](https://bugs.python.org/issue26081) \[https://bugs.python.org/issue26081\]and [bpo-28544](https://bugs.python.org/issue28544) \[https://bugs.python.org/issue28544\].) ### binascii The [`b2a_base64()`](../library/binascii.xhtml#binascii.b2a_base64 "binascii.b2a_base64") function now accepts an optional *newline*keyword argument to control whether the newline character is appended to the return value. (Contributed by Victor Stinner in [bpo-25357](https://bugs.python.org/issue25357) \[https://bugs.python.org/issue25357\].) ### cmath The new [`cmath.tau`](../library/cmath.xhtml#cmath.tau "cmath.tau") (*τ*) constant has been added. (Contributed by Lisa Roach in [bpo-12345](https://bugs.python.org/issue12345) \[https://bugs.python.org/issue12345\], see [**PEP 628**](https://www.python.org/dev/peps/pep-0628) \[https://www.python.org/dev/peps/pep-0628\] for details.) New constants: [`cmath.inf`](../library/cmath.xhtml#cmath.inf "cmath.inf") and [`cmath.nan`](../library/cmath.xhtml#cmath.nan "cmath.nan") to match [`math.inf`](../library/math.xhtml#math.inf "math.inf") and [`math.nan`](../library/math.xhtml#math.nan "math.nan"), and also [`cmath.infj`](../library/cmath.xhtml#cmath.infj "cmath.infj")and [`cmath.nanj`](../library/cmath.xhtml#cmath.nanj "cmath.nanj") to match the format used by complex repr. (Contributed by Mark Dickinson in [bpo-23229](https://bugs.python.org/issue23229) \[https://bugs.python.org/issue23229\].) ### collections The new [`Collection`](../library/collections.abc.xhtml#collections.abc.Collection "collections.abc.Collection") abstract base class has been added to represent sized iterable container classes. (Contributed by Ivan Levkivskyi, docs by Neil Girdhar in [bpo-27598](https://bugs.python.org/issue27598) \[https://bugs.python.org/issue27598\].) The new [`Reversible`](../library/collections.abc.xhtml#collections.abc.Reversible "collections.abc.Reversible") abstract base class represents iterable classes that also provide the [`__reversed__()`](../reference/datamodel.xhtml#object.__reversed__ "object.__reversed__") method. (Contributed by Ivan Levkivskyi in [bpo-25987](https://bugs.python.org/issue25987) \[https://bugs.python.org/issue25987\].) The new [`AsyncGenerator`](../library/collections.abc.xhtml#collections.abc.AsyncGenerator "collections.abc.AsyncGenerator") abstract base class represents asynchronous generators. (Contributed by Yury Selivanov in [bpo-28720](https://bugs.python.org/issue28720) \[https://bugs.python.org/issue28720\].) The [`namedtuple()`](../library/collections.xhtml#collections.namedtuple "collections.namedtuple") function now accepts an optional keyword argument *module*, which, when specified, is used for the `__module__` attribute of the returned named tuple class. (Contributed by Raymond Hettinger in [bpo-17941](https://bugs.python.org/issue17941) \[https://bugs.python.org/issue17941\].) The *verbose* and *rename* arguments for [`namedtuple()`](../library/collections.xhtml#collections.namedtuple "collections.namedtuple") are now keyword-only. (Contributed by Raymond Hettinger in [bpo-25628](https://bugs.python.org/issue25628) \[https://bugs.python.org/issue25628\].) Recursive [`collections.deque`](../library/collections.xhtml#collections.deque "collections.deque") instances can now be pickled. (Contributed by Serhiy Storchaka in [bpo-26482](https://bugs.python.org/issue26482) \[https://bugs.python.org/issue26482\].) ### concurrent.futures The [`ThreadPoolExecutor`](../library/concurrent.futures.xhtml#concurrent.futures.ThreadPoolExecutor "concurrent.futures.ThreadPoolExecutor")class constructor now accepts an optional *thread\_name\_prefix* argument to make it possible to customize the names of the threads created by the pool. (Contributed by Gregory P. Smith in [bpo-27664](https://bugs.python.org/issue27664) \[https://bugs.python.org/issue27664\].) ### contextlib The [`contextlib.AbstractContextManager`](../library/contextlib.xhtml#contextlib.AbstractContextManager "contextlib.AbstractContextManager") class has been added to provide an abstract base class for context managers. It provides a sensible default implementation for \_\_enter\_\_() which returns `self` and leaves \_\_exit\_\_() an abstract method. A matching class has been added to the [`typing`](../library/typing.xhtml#module-typing "typing: Support for type hints (see PEP 484).") module as [`typing.ContextManager`](../library/typing.xhtml#typing.ContextManager "typing.ContextManager"). (Contributed by Brett Cannon in [bpo-25609](https://bugs.python.org/issue25609) \[https://bugs.python.org/issue25609\].) ### datetime The [`datetime`](../library/datetime.xhtml#datetime.datetime "datetime.datetime") and [`time`](../library/datetime.xhtml#datetime.time "datetime.time") classes have the new `fold` attribute used to disambiguate local time when necessary. Many functions in the [`datetime`](../library/datetime.xhtml#module-datetime "datetime: Basic date and time types.") have been updated to support local time disambiguation. See [Local Time Disambiguation](#whatsnew36-pep495) section for more information. (Contributed by Alexander Belopolsky in [bpo-24773](https://bugs.python.org/issue24773) \[https://bugs.python.org/issue24773\].) The [`datetime.strftime()`](../library/datetime.xhtml#datetime.datetime.strftime "datetime.datetime.strftime") and [`date.strftime()`](../library/datetime.xhtml#datetime.date.strftime "datetime.date.strftime") methods now support ISO 8601 date directives `%G`, `%u` and `%V`. (Contributed by Ashley Anderson in [bpo-12006](https://bugs.python.org/issue12006) \[https://bugs.python.org/issue12006\].) The [`datetime.isoformat()`](../library/datetime.xhtml#datetime.datetime.isoformat "datetime.datetime.isoformat") function now accepts an optional *timespec* argument that specifies the number of additional components of the time value to include. (Contributed by Alessandro Cucci and Alexander Belopolsky in [bpo-19475](https://bugs.python.org/issue19475) \[https://bugs.python.org/issue19475\].) The [`datetime.combine()`](../library/datetime.xhtml#datetime.datetime.combine "datetime.datetime.combine") now accepts an optional *tzinfo* argument. (Contributed by Alexander Belopolsky in [bpo-27661](https://bugs.python.org/issue27661) \[https://bugs.python.org/issue27661\].) ### decimal New [`Decimal.as_integer_ratio()`](../library/decimal.xhtml#decimal.Decimal.as_integer_ratio "decimal.Decimal.as_integer_ratio")method that returns a pair `(n, d)` of integers that represent the given [`Decimal`](../library/decimal.xhtml#decimal.Decimal "decimal.Decimal") instance as a fraction, in lowest terms and with a positive denominator: ``` >>> Decimal('-3.14').as_integer_ratio() (-157, 50) ``` (Contributed by Stefan Krah amd Mark Dickinson in [bpo-25928](https://bugs.python.org/issue25928) \[https://bugs.python.org/issue25928\].) ### distutils The `default_format` attribute has been removed from `distutils.command.sdist.sdist` and the `formats`attribute defaults to `['gztar']`. Although not anticipated, any code relying on the presence of `default_format` may need to be adapted. See [bpo-27819](https://bugs.python.org/issue27819) \[https://bugs.python.org/issue27819\] for more details. ### email The new email API, enabled via the *policy* keyword to various constructors, is no longer provisional. The [`email`](../library/email.xhtml#module-email "email: Package supporting the parsing, manipulating, and generating email messages.") documentation has been reorganized and rewritten to focus on the new API, while retaining the old documentation for the legacy API. (Contributed by R. David Murray in [bpo-24277](https://bugs.python.org/issue24277) \[https://bugs.python.org/issue24277\].) The [`email.mime`](../library/email.mime.xhtml#module-email.mime "email.mime: Build MIME messages.") classes now all accept an optional *policy* keyword. (Contributed by Berker Peksag in [bpo-27331](https://bugs.python.org/issue27331) \[https://bugs.python.org/issue27331\].) The [`DecodedGenerator`](../library/email.generator.xhtml#email.generator.DecodedGenerator "email.generator.DecodedGenerator") now supports the *policy*keyword. There is a new [`policy`](../library/email.policy.xhtml#module-email.policy "email.policy: Controlling the parsing and generating of messages") attribute, [`message_factory`](../library/email.policy.xhtml#email.policy.Policy.message_factory "email.policy.Policy.message_factory"), that controls what class is used by default when the parser creates new message objects. For the [`email.policy.compat32`](../library/email.policy.xhtml#email.policy.compat32 "email.policy.compat32") policy this is [`Message`](../library/email.compat32-message.xhtml#email.message.Message "email.message.Message"), for the new policies it is [`EmailMessage`](../library/email.message.xhtml#email.message.EmailMessage "email.message.EmailMessage"). (Contributed by R. David Murray in [bpo-20476](https://bugs.python.org/issue20476) \[https://bugs.python.org/issue20476\].) ### encodings On Windows, added the `'oem'` encoding to use `CP_OEMCP`, and the `'ansi'`alias for the existing `'mbcs'` encoding, which uses the `CP_ACP` code page. (Contributed by Steve Dower in [bpo-27959](https://bugs.python.org/issue27959) \[https://bugs.python.org/issue27959\].) ### enum Two new enumeration base classes have been added to the [`enum`](../library/enum.xhtml#module-enum "enum: Implementation of an enumeration class.") module: [`Flag`](../library/enum.xhtml#enum.Flag "enum.Flag") and `IntFlags`. Both are used to define constants that can be combined using the bitwise operators. (Contributed by Ethan Furman in [bpo-23591](https://bugs.python.org/issue23591) \[https://bugs.python.org/issue23591\].) Many standard library modules have been updated to use the `IntFlags` class for their constants. The new [`enum.auto`](../library/enum.xhtml#enum.auto "enum.auto") value can be used to assign values to enum members automatically: ``` >>> from enum import Enum, auto >>> class Color(Enum): ... red = auto() ... blue = auto() ... green = auto() ... >>> list(Color) [<Color.red: 1>, <Color.blue: 2>, <Color.green: 3>] ``` ### faulthandler On Windows, the [`faulthandler`](../library/faulthandler.xhtml#module-faulthandler "faulthandler: Dump the Python traceback.") module now installs a handler for Windows exceptions: see [`faulthandler.enable()`](../library/faulthandler.xhtml#faulthandler.enable "faulthandler.enable"). (Contributed by Victor Stinner in [bpo-23848](https://bugs.python.org/issue23848) \[https://bugs.python.org/issue23848\].) ### fileinput [`hook_encoded()`](../library/fileinput.xhtml#fileinput.hook_encoded "fileinput.hook_encoded") now supports the *errors* argument. (Contributed by Joseph Hackman in [bpo-25788](https://bugs.python.org/issue25788) \[https://bugs.python.org/issue25788\].) ### hashlib [`hashlib`](../library/hashlib.xhtml#module-hashlib "hashlib: Secure hash and message digest algorithms.") supports OpenSSL 1.1.0. The minimum recommend version is 1.0.2. (Contributed by Christian Heimes in [bpo-26470](https://bugs.python.org/issue26470) \[https://bugs.python.org/issue26470\].) BLAKE2 hash functions were added to the module. [`blake2b()`](../library/hashlib.xhtml#hashlib.blake2b "hashlib.blake2b")and [`blake2s()`](../library/hashlib.xhtml#hashlib.blake2s "hashlib.blake2s") are always available and support the full feature set of BLAKE2. (Contributed by Christian Heimes in [bpo-26798](https://bugs.python.org/issue26798) \[https://bugs.python.org/issue26798\] based on code by Dmitry Chestnykh and Samuel Neves. Documentation written by Dmitry Chestnykh.) The SHA-3 hash functions `sha3_224()`, `sha3_256()`, `sha3_384()`, `sha3_512()`, and SHAKE hash functions `shake_128()` and `shake_256()` were added. (Contributed by Christian Heimes in [bpo-16113](https://bugs.python.org/issue16113) \[https://bugs.python.org/issue16113\]. Keccak Code Package by Guido Bertoni, Joan Daemen, Michaël Peeters, Gilles Van Assche, and Ronny Van Keer.) The password-based key derivation function [`scrypt()`](../library/hashlib.xhtml#hashlib.scrypt "hashlib.scrypt") is now available with OpenSSL 1.1.0 and newer. (Contributed by Christian Heimes in [bpo-27928](https://bugs.python.org/issue27928) \[https://bugs.python.org/issue27928\].) ### http.client [`HTTPConnection.request()`](../library/http.client.xhtml#http.client.HTTPConnection.request "http.client.HTTPConnection.request") and [`endheaders()`](../library/http.client.xhtml#http.client.HTTPConnection.endheaders "http.client.HTTPConnection.endheaders") both now support chunked encoding request bodies. (Contributed by Demian Brecht and Rolf Krahl in [bpo-12319](https://bugs.python.org/issue12319) \[https://bugs.python.org/issue12319\].) ### idlelib 与 IDLE The idlelib package is being modernized and refactored to make IDLE look and work better and to make the code easier to understand, test, and improve. Part of making IDLE look better, especially on Linux and Mac, is using ttk widgets, mostly in the dialogs. As a result, IDLE no longer runs with tcl/tk 8.4. It now requires tcl/tk 8.5 or 8.6. We recommend running the latest release of either. 'Modernizing' includes renaming and consolidation of idlelib modules. The renaming of files with partial uppercase names is similar to the renaming of, for instance, Tkinter and TkFont to tkinter and tkinter.font in 3.0. As a result, imports of idlelib files that worked in 3.5 will usually not work in 3.6. At least a module name change will be needed (see idlelib/README.txt), sometimes more. (Name changes contributed by Al Swiegart and Terry Reedy in [bpo-24225](https://bugs.python.org/issue24225) \[https://bugs.python.org/issue24225\]. Most idlelib patches since have been and will be part of the process.) In compensation, the eventual result with be that some idlelib classes will be easier to use, with better APIs and docstrings explaining them. Additional useful information will be added to idlelib when available. New in 3.6.2: 多个对自动补全的修正。 （由 Louie Lu 在 [bpo-15786](https://bugs.python.org/issue15786) \[https://bugs.python.org/issue15786\] 中贡献。） New in 3.6.3: Module Browser (在 File 菜单中，之前称为 Class Browser) 现在会在最高层级函数和类之外显示嵌套的函数和类。 （由 Guilherme Polo, Cheryl Sabella 和 Terry Jan Reedy 在 [bpo-1612262](https://bugs.python.org/issue1612262) \[https://bugs.python.org/issue1612262\] 中贡献。） 之前以扩展形式实现的 IDLE 特性已作为正常特性重新实现。 它们的设置已从 Extensions 选项卡移至其他对话框选项卡。 （由 Charles Wohlganger 和 Terry Jan Reedy 在 [bpo-27099](https://bugs.python.org/issue27099) \[https://bugs.python.org/issue27099\] 中实现。） Settings 对话框 (Options 中的 Configure IDLE) 已经被部分重写以改进外观和功能。 （由 Cheryl Sabella 和 Terry Jan Reedy 在多个问题项中贡献。） New in 3.6.4: 字体样本现在包括一组非拉丁字符以便用户能更好地查看所选特定字体的效果。 （由 Terry Jan Reedy 在 [bpo-13802](https://bugs.python.org/issue13802) \[https://bugs.python.org/issue13802\] 中贡献。） 样本可以被修改以包括其他字符。 （由 Serhiy Storchaka 在 [bpo-31860](https://bugs.python.org/issue31860) \[https://bugs.python.org/issue31860\] 中贡献。） New in 3.6.6: 编辑器代码上下文选项已经过修改。 Box 会显示所有上下文行直到最大行数。 点击一个上下文行会使编辑器跳转到该行。 自定义主题的上下文颜色已添加到 Settings 对话框的 Highlights 选项卡。 （由 Cheryl Sabella 和 Terry Jan Reedy 在 [bpo-33642](https://bugs.python.org/issue33642) \[https://bugs.python.org/issue33642\], [bpo-33768](https://bugs.python.org/issue33768) \[https://bugs.python.org/issue33768\] 和 [bpo-33679](https://bugs.python.org/issue33679) \[https://bugs.python.org/issue33679\] 中贡献。） 在 Windows 上，会有新的 API 调用将 tk 对 DPI 的调整告知 Windows。 在 Windows 8.1+ 或 10 上，如果 Python 二进制码的 DPI 兼容属性未改变，并且监视器分辨率大于 96 DPI，这应该会令文本和线条更清晰。 否则的话它应该不造成影响。 （由 Terry Jan Reedy 在 [bpo-33656](https://bugs.python.org/issue33656) \[https://bugs.python.org/issue33656\] 中贡献。） New in 3.6.7: 超过 N 行（默认值为 50）的输出将被折叠为一个按钮。 N 可以在 Settings 对话框的 General 页的 PyShell 部分中进行修改。 数量较少但是超长的行可以通过在输出上右击来折叠。 被折叠的输出可通过双击按钮来展开，或是通过右击按钮来放入剪贴板或是单独的窗口。 （由 Tal Einat 在 [bpo-1529353](https://bugs.python.org/issue1529353) \[https://bugs.python.org/issue1529353\] 中贡献。） ### importlib Import now raises the new exception [`ModuleNotFoundError`](../library/exceptions.xhtml#ModuleNotFoundError "ModuleNotFoundError")(subclass of [`ImportError`](../library/exceptions.xhtml#ImportError "ImportError")) when it cannot find a module. Code that current checks for `ImportError` (in try-except) will still work. (Contributed by Eric Snow in [bpo-15767](https://bugs.python.org/issue15767) \[https://bugs.python.org/issue15767\].) [`importlib.util.LazyLoader`](../library/importlib.xhtml#importlib.util.LazyLoader "importlib.util.LazyLoader") now calls [`create_module()`](../library/importlib.xhtml#importlib.abc.Loader.create_module "importlib.abc.Loader.create_module") on the wrapped loader, removing the restriction that [`importlib.machinery.BuiltinImporter`](../library/importlib.xhtml#importlib.machinery.BuiltinImporter "importlib.machinery.BuiltinImporter") and [`importlib.machinery.ExtensionFileLoader`](../library/importlib.xhtml#importlib.machinery.ExtensionFileLoader "importlib.machinery.ExtensionFileLoader") couldn't be used with [`importlib.util.LazyLoader`](../library/importlib.xhtml#importlib.util.LazyLoader "importlib.util.LazyLoader"). [`importlib.util.cache_from_source()`](../library/importlib.xhtml#importlib.util.cache_from_source "importlib.util.cache_from_source"), [`importlib.util.source_from_cache()`](../library/importlib.xhtml#importlib.util.source_from_cache "importlib.util.source_from_cache"), and [`importlib.util.spec_from_file_location()`](../library/importlib.xhtml#importlib.util.spec_from_file_location "importlib.util.spec_from_file_location") now accept a [path-like object](../glossary.xhtml#term-path-like-object). ### inspect The [`inspect.signature()`](../library/inspect.xhtml#inspect.signature "inspect.signature") function now reports the implicit `.0` parameters generated by the compiler for comprehension and generator expression scopes as if they were positional-only parameters called `implicit0`. (Contributed by Jelle Zijlstra in [bpo-19611](https://bugs.python.org/issue19611) \[https://bugs.python.org/issue19611\].) To reduce code churn when upgrading from Python 2.7 and the legacy [`inspect.getargspec()`](../library/inspect.xhtml#inspect.getargspec "inspect.getargspec") API, the previously documented deprecation of [`inspect.getfullargspec()`](../library/inspect.xhtml#inspect.getfullargspec "inspect.getfullargspec") has been reversed. While this function is convenient for single/source Python 2/3 code bases, the richer [`inspect.signature()`](../library/inspect.xhtml#inspect.signature "inspect.signature") interface remains the recommended approach for new code. (Contributed by Nick Coghlan in [bpo-27172](https://bugs.python.org/issue27172) \[https://bugs.python.org/issue27172\]) ### json [`json.load()`](../library/json.xhtml#json.load "json.load") and [`json.loads()`](../library/json.xhtml#json.loads "json.loads") now support binary input. Encoded JSON should be represented using either UTF-8, UTF-16, or UTF-32. (Contributed by Serhiy Storchaka in [bpo-17909](https://bugs.python.org/issue17909) \[https://bugs.python.org/issue17909\].) ### logging The new [`WatchedFileHandler.reopenIfNeeded()`](../library/logging.handlers.xhtml#logging.handlers.WatchedFileHandler.reopenIfNeeded "logging.handlers.WatchedFileHandler.reopenIfNeeded")method has been added to add the ability to check if the log file needs to be reopened. (Contributed by Marian Horban in [bpo-24884](https://bugs.python.org/issue24884) \[https://bugs.python.org/issue24884\].) ### math The tau (*τ*) constant has been added to the [`math`](../library/math.xhtml#module-math "math: Mathematical functions (sin() etc.).") and [`cmath`](../library/cmath.xhtml#module-cmath "cmath: Mathematical functions for complex numbers.")modules. (Contributed by Lisa Roach in [bpo-12345](https://bugs.python.org/issue12345) \[https://bugs.python.org/issue12345\], see [**PEP 628**](https://www.python.org/dev/peps/pep-0628) \[https://www.python.org/dev/peps/pep-0628\] for details.) ### multiprocessing [Proxy Objects](../library/multiprocessing.xhtml#multiprocessing-proxy-objects) returned by `multiprocessing.Manager()` can now be nested. (Contributed by Davin Potts in [bpo-6766](https://bugs.python.org/issue6766) \[https://bugs.python.org/issue6766\].) ### os See the summary of [PEP 519](#whatsnew36-pep519) for details on how the [`os`](../library/os.xhtml#module-os "os: Miscellaneous operating system interfaces.") and [`os.path`](../library/os.path.xhtml#module-os.path "os.path: Operations on pathnames.") modules now support [path-like objects](../glossary.xhtml#term-path-like-object). [`scandir()`](../library/os.xhtml#os.scandir "os.scandir") now supports [`bytes`](../library/stdtypes.xhtml#bytes "bytes") paths on Windows. A new [`close()`](../library/os.xhtml#os.scandir.close "os.scandir.close") method allows explicitly closing a [`scandir()`](../library/os.xhtml#os.scandir "os.scandir") iterator. The [`scandir()`](../library/os.xhtml#os.scandir "os.scandir") iterator now supports the [context manager](../glossary.xhtml#term-context-manager) protocol. If a `scandir()`iterator is neither exhausted nor explicitly closed a [`ResourceWarning`](../library/exceptions.xhtml#ResourceWarning "ResourceWarning")will be emitted in its destructor. (Contributed by Serhiy Storchaka in [bpo-25994](https://bugs.python.org/issue25994) \[https://bugs.python.org/issue25994\].) On Linux, [`os.urandom()`](../library/os.xhtml#os.urandom "os.urandom") now blocks until the system urandom entropy pool is initialized to increase the security. See the [**PEP 524**](https://www.python.org/dev/peps/pep-0524) \[https://www.python.org/dev/peps/pep-0524\] for the rationale. The Linux `getrandom()` syscall (get random bytes) is now exposed as the new [`os.getrandom()`](../library/os.xhtml#os.getrandom "os.getrandom") function. (Contributed by Victor Stinner, part of the [**PEP 524**](https://www.python.org/dev/peps/pep-0524) \[https://www.python.org/dev/peps/pep-0524\]) ### pathlib [`pathlib`](../library/pathlib.xhtml#module-pathlib "pathlib: Object-oriented filesystem paths") now supports [path-like objects](../glossary.xhtml#term-path-like-object). (Contributed by Brett Cannon in [bpo-27186](https://bugs.python.org/issue27186) \[https://bugs.python.org/issue27186\].) See the summary of [PEP 519](#whatsnew36-pep519) for details. ### pdb The [`Pdb`](../library/pdb.xhtml#pdb.Pdb "pdb.Pdb") class constructor has a new optional *readrc* argument to control whether `.pdbrc` files should be read. ### pickle Objects that need `__new__` called with keyword arguments can now be pickled using [pickle protocols](../library/pickle.xhtml#pickle-protocols) older than protocol version 4. Protocol version 4 already supports this case. (Contributed by Serhiy Storchaka in [bpo-24164](https://bugs.python.org/issue24164) \[https://bugs.python.org/issue24164\].) ### pickletools [`pickletools.dis()`](../library/pickletools.xhtml#pickletools.dis "pickletools.dis") now outputs the implicit memo index for the `MEMOIZE` opcode. (Contributed by Serhiy Storchaka in [bpo-25382](https://bugs.python.org/issue25382) \[https://bugs.python.org/issue25382\].) ### pydoc The [`pydoc`](../library/pydoc.xhtml#module-pydoc "pydoc: Documentation generator and online help system.") module has learned to respect the `MANPAGER`environment variable. (Contributed by Matthias Klose in [bpo-8637](https://bugs.python.org/issue8637) \[https://bugs.python.org/issue8637\].) [`help()`](../library/functions.xhtml#help "help") and [`pydoc`](../library/pydoc.xhtml#module-pydoc "pydoc: Documentation generator and online help system.") can now list named tuple fields in the order they were defined rather than alphabetically. (Contributed by Raymond Hettinger in [bpo-24879](https://bugs.python.org/issue24879) \[https://bugs.python.org/issue24879\].) ### random The new [`choices()`](../library/random.xhtml#random.choices "random.choices") function returns a list of elements of specified size from the given population with optional weights. (Contributed by Raymond Hettinger in [bpo-18844](https://bugs.python.org/issue18844) \[https://bugs.python.org/issue18844\].) ### re Added support of modifier spans in regular expressions. Examples: `'(?i:p)ython'` matches `'python'` and `'Python'`, but not `'PYTHON'`; `'(?i)g(?-i:v)r'` matches `'GvR'` and `'gvr'`, but not `'GVR'`. (Contributed by Serhiy Storchaka in [bpo-433028](https://bugs.python.org/issue433028) \[https://bugs.python.org/issue433028\].) Match object groups can be accessed by `__getitem__`, which is equivalent to `group()`. So `mo['name']` is now equivalent to `mo.group('name')`. (Contributed by Eric Smith in [bpo-24454](https://bugs.python.org/issue24454) \[https://bugs.python.org/issue24454\].) `Match` objects now support [`index-like objects`](../reference/datamodel.xhtml#object.__index__ "object.__index__") as group indices. (Contributed by Jeroen Demeyer and Xiang Zhang in [bpo-27177](https://bugs.python.org/issue27177) \[https://bugs.python.org/issue27177\].) ### readline Added [`set_auto_history()`](../library/readline.xhtml#readline.set_auto_history "readline.set_auto_history") to enable or disable automatic addition of input to the history list. (Contributed by Tyler Crompton in [bpo-26870](https://bugs.python.org/issue26870) \[https://bugs.python.org/issue26870\].) ### rlcompleter Private and special attribute names now are omitted unless the prefix starts with underscores. A space or a colon is added after some completed keywords. (Contributed by Serhiy Storchaka in [bpo-25011](https://bugs.python.org/issue25011) \[https://bugs.python.org/issue25011\] and [bpo-25209](https://bugs.python.org/issue25209) \[https://bugs.python.org/issue25209\].) ### shlex The [`shlex`](../library/shlex.xhtml#shlex.shlex "shlex.shlex") has much [improved shell compatibility](../library/shlex.xhtml#improved-shell-compatibility)through the new *punctuation\_chars* argument to control which characters are treated as punctuation. (Contributed by Vinay Sajip in [bpo-1521950](https://bugs.python.org/issue1521950) \[https://bugs.python.org/issue1521950\].) ### site When specifying paths to add to [`sys.path`](../library/sys.xhtml#sys.path "sys.path") in a .pth file, you may now specify file paths on top of directories (e.g. zip files). (Contributed by Wolfgang Langner in [bpo-26587](https://bugs.python.org/issue26587) \[https://bugs.python.org/issue26587\]). ### sqlite3 [`sqlite3.Cursor.lastrowid`](../library/sqlite3.xhtml#sqlite3.Cursor.lastrowid "sqlite3.Cursor.lastrowid") now supports the `REPLACE` statement. (Contributed by Alex LordThorsen in [bpo-16864](https://bugs.python.org/issue16864) \[https://bugs.python.org/issue16864\].) ### socket The [`ioctl()`](../library/socket.xhtml#socket.socket.ioctl "socket.socket.ioctl") function now supports the [`SIO_LOOPBACK_FAST_PATH`](../library/socket.xhtml#socket.SIO_LOOPBACK_FAST_PATH "socket.SIO_LOOPBACK_FAST_PATH") control code. (Contributed by Daniel Stokes in [bpo-26536](https://bugs.python.org/issue26536) \[https://bugs.python.org/issue26536\].) The [`getsockopt()`](../library/socket.xhtml#socket.socket.getsockopt "socket.socket.getsockopt") constants `SO_DOMAIN`, `SO_PROTOCOL`, `SO_PEERSEC`, and `SO_PASSSEC` are now supported. (Contributed by Christian Heimes in [bpo-26907](https://bugs.python.org/issue26907) \[https://bugs.python.org/issue26907\].) The [`setsockopt()`](../library/socket.xhtml#socket.socket.setsockopt "socket.socket.setsockopt") now supports the `setsockopt(level, optname, None, optlen: int)` form. (Contributed by Christian Heimes in [bpo-27744](https://bugs.python.org/issue27744) \[https://bugs.python.org/issue27744\].) The socket module now supports the address family [`AF_ALG`](../library/socket.xhtml#socket.AF_ALG "socket.AF_ALG") to interface with Linux Kernel crypto API. `ALG_*`, `SOL_ALG` and [`sendmsg_afalg()`](../library/socket.xhtml#socket.socket.sendmsg_afalg "socket.socket.sendmsg_afalg") were added. (Contributed by Christian Heimes in [bpo-27744](https://bugs.python.org/issue27744) \[https://bugs.python.org/issue27744\] with support from Victor Stinner.) New Linux constants `TCP_USER_TIMEOUT` and `TCP_CONGESTION` were added. (Contributed by Omar Sandoval, issue:26273). ### socketserver Servers based on the [`socketserver`](../library/socketserver.xhtml#module-socketserver "socketserver: A framework for network servers.") module, including those defined in [`http.server`](../library/http.server.xhtml#module-http.server "http.server: HTTP server and request handlers."), [`xmlrpc.server`](../library/xmlrpc.server.xhtml#module-xmlrpc.server "xmlrpc.server: Basic XML-RPC server implementations.") and [`wsgiref.simple_server`](../library/wsgiref.xhtml#module-wsgiref.simple_server "wsgiref.simple_server: A simple WSGI HTTP server."), now support the [context manager](../glossary.xhtml#term-context-manager)protocol. (Contributed by Aviv Palivoda in [bpo-26404](https://bugs.python.org/issue26404) \[https://bugs.python.org/issue26404\].) The `wfile` attribute of [`StreamRequestHandler`](../library/socketserver.xhtml#socketserver.StreamRequestHandler "socketserver.StreamRequestHandler") classes now implements the [`io.BufferedIOBase`](../library/io.xhtml#io.BufferedIOBase "io.BufferedIOBase") writable interface. In particular, calling [`write()`](../library/io.xhtml#io.BufferedIOBase.write "io.BufferedIOBase.write") is now guaranteed to send the data in full. (Contributed by Martin Panter in [bpo-26721](https://bugs.python.org/issue26721) \[https://bugs.python.org/issue26721\].) ### ssl [`ssl`](../library/ssl.xhtml#module-ssl "ssl: TLS/SSL wrapper for socket objects") supports OpenSSL 1.1.0. The minimum recommend version is 1.0.2. (Contributed by Christian Heimes in [bpo-26470](https://bugs.python.org/issue26470) \[https://bugs.python.org/issue26470\].) 3DES has been removed from the default cipher suites and ChaCha20 Poly1305 cipher suites have been added. (Contributed by Christian Heimes in [bpo-27850](https://bugs.python.org/issue27850) \[https://bugs.python.org/issue27850\] and [bpo-27766](https://bugs.python.org/issue27766) \[https://bugs.python.org/issue27766\].) [`SSLContext`](../library/ssl.xhtml#ssl.SSLContext "ssl.SSLContext") has better default configuration for options and ciphers. (Contributed by Christian Heimes in [bpo-28043](https://bugs.python.org/issue28043) \[https://bugs.python.org/issue28043\].) SSL session can be copied from one client-side connection to another with the new [`SSLSession`](../library/ssl.xhtml#ssl.SSLSession "ssl.SSLSession") class. TLS session resumption can speed up the initial handshake, reduce latency and improve performance (Contributed by Christian Heimes in [bpo-19500](https://bugs.python.org/issue19500) \[https://bugs.python.org/issue19500\] based on a draft by Alex Warhawk.) The new [`get_ciphers()`](../library/ssl.xhtml#ssl.SSLContext.get_ciphers "ssl.SSLContext.get_ciphers") method can be used to get a list of enabled ciphers in order of cipher priority. All constants and flags have been converted to [`IntEnum`](../library/enum.xhtml#enum.IntEnum "enum.IntEnum") and `IntFlags`. (Contributed by Christian Heimes in [bpo-28025](https://bugs.python.org/issue28025) \[https://bugs.python.org/issue28025\].) Server and client-side specific TLS protocols for [`SSLContext`](../library/ssl.xhtml#ssl.SSLContext "ssl.SSLContext")were added. (Contributed by Christian Heimes in [bpo-28085](https://bugs.python.org/issue28085) \[https://bugs.python.org/issue28085\].) ### statistics A new [`harmonic_mean()`](../library/statistics.xhtml#statistics.harmonic_mean "statistics.harmonic_mean") function has been added. (Contributed by Steven D'Aprano in [bpo-27181](https://bugs.python.org/issue27181) \[https://bugs.python.org/issue27181\].) ### struct [`struct`](../library/struct.xhtml#module-struct "struct: Interpret bytes as packed binary data.") now supports IEEE 754 half-precision floats via the `'e'`format specifier. (Contributed by Eli Stevens, Mark Dickinson in [bpo-11734](https://bugs.python.org/issue11734) \[https://bugs.python.org/issue11734\].) ### subprocess [`subprocess.Popen`](../library/subprocess.xhtml#subprocess.Popen "subprocess.Popen") destructor now emits a [`ResourceWarning`](../library/exceptions.xhtml#ResourceWarning "ResourceWarning") warning if the child process is still running. Use the context manager protocol ( ``` with proc: ... ``` ) or explicitly call the [`wait()`](../library/subprocess.xhtml#subprocess.Popen.wait "subprocess.Popen.wait") method to read the exit status of the child process. (Contributed by Victor Stinner in [bpo-26741](https://bugs.python.org/issue26741) \[https://bugs.python.org/issue26741\].) The [`subprocess.Popen`](../library/subprocess.xhtml#subprocess.Popen "subprocess.Popen") constructor and all functions that pass arguments through to it now accept *encoding* and *errors* arguments. Specifying either of these will enable text mode for the *stdin*, *stdout* and *stderr* streams. (Contributed by Steve Dower in [bpo-6135](https://bugs.python.org/issue6135) \[https://bugs.python.org/issue6135\].) ### sys The new [`getfilesystemencodeerrors()`](../library/sys.xhtml#sys.getfilesystemencodeerrors "sys.getfilesystemencodeerrors") function returns the name of the error mode used to convert between Unicode filenames and bytes filenames. (Contributed by Steve Dower in [bpo-27781](https://bugs.python.org/issue27781) \[https://bugs.python.org/issue27781\].) On Windows the return value of the [`getwindowsversion()`](../library/sys.xhtml#sys.getwindowsversion "sys.getwindowsversion") function now includes the *platform\_version* field which contains the accurate major version, minor version and build number of the current operating system, rather than the version that is being emulated for the process (Contributed by Steve Dower in [bpo-27932](https://bugs.python.org/issue27932) \[https://bugs.python.org/issue27932\].) ### telnetlib [`Telnet`](../library/telnetlib.xhtml#telnetlib.Telnet "telnetlib.Telnet") is now a context manager (contributed by Stéphane Wirtel in [bpo-25485](https://bugs.python.org/issue25485) \[https://bugs.python.org/issue25485\]). ### time The [`struct_time`](../library/time.xhtml#time.struct_time "time.struct_time") attributes `tm_gmtoff` and `tm_zone` are now available on all platforms. ### timeit The new [`Timer.autorange()`](../library/timeit.xhtml#timeit.Timer.autorange "timeit.Timer.autorange") convenience method has been added to call [`Timer.timeit()`](../library/timeit.xhtml#timeit.Timer.timeit "timeit.Timer.timeit")repeatedly so that the total run time is greater or equal to 200 milliseconds. (Contributed by Steven D'Aprano in [bpo-6422](https://bugs.python.org/issue6422) \[https://bugs.python.org/issue6422\].) [`timeit`](../library/timeit.xhtml#module-timeit "timeit: Measure the execution time of small code snippets.") now warns when there is substantial (4x) variance between best and worst times. (Contributed by Serhiy Storchaka in [bpo-23552](https://bugs.python.org/issue23552) \[https://bugs.python.org/issue23552\].) ### tkinter Added methods `trace_add()`, `trace_remove()` and `trace_info()`in the `tkinter.Variable` class. They replace old methods `trace_variable()`, `trace()`, `trace_vdelete()` and `trace_vinfo()` that use obsolete Tcl commands and might not work in future versions of Tcl. (Contributed by Serhiy Storchaka in [bpo-22115](https://bugs.python.org/issue22115) \[https://bugs.python.org/issue22115\]). ### traceback Both the traceback module and the interpreter's builtin exception display now abbreviate long sequences of repeated lines in tracebacks as shown in the following example: ``` >>> def f(): f() ... >>> f() Traceback (most recent call last): File "<stdin>", line 1, in <module> File "<stdin>", line 1, in f File "<stdin>", line 1, in f File "<stdin>", line 1, in f [Previous line repeated 995 more times] RecursionError: maximum recursion depth exceeded ``` (Contributed by Emanuel Barry in [bpo-26823](https://bugs.python.org/issue26823) \[https://bugs.python.org/issue26823\].) ### tracemalloc The [`tracemalloc`](../library/tracemalloc.xhtml#module-tracemalloc "tracemalloc: Trace memory allocations.") module now supports tracing memory allocations in multiple different address spaces. The new [`DomainFilter`](../library/tracemalloc.xhtml#tracemalloc.DomainFilter "tracemalloc.DomainFilter") filter class has been added to filter block traces by their address space (domain). (Contributed by Victor Stinner in [bpo-26588](https://bugs.python.org/issue26588) \[https://bugs.python.org/issue26588\].) ### typing Since the [`typing`](../library/typing.xhtml#module-typing "typing: Support for type hints (see PEP 484).") module is [provisional](../glossary.xhtml#term-provisional-api), all changes introduced in Python 3.6 have also been backported to Python 3.5.x. The [`typing`](../library/typing.xhtml#module-typing "typing: Support for type hints (see PEP 484).") module has a much improved support for generic type aliases. For example `Dict[str, Tuple[S, T]]` is now a valid type annotation. (Contributed by Guido van Rossum in [Github #195](https://github.com/python/typing/pull/195) \[https://github.com/python/typing/pull/195\].) The [`typing.ContextManager`](../library/typing.xhtml#typing.ContextManager "typing.ContextManager") class has been added for representing [`contextlib.AbstractContextManager`](../library/contextlib.xhtml#contextlib.AbstractContextManager "contextlib.AbstractContextManager"). (Contributed by Brett Cannon in [bpo-25609](https://bugs.python.org/issue25609) \[https://bugs.python.org/issue25609\].) The [`typing.Collection`](../library/typing.xhtml#typing.Collection "typing.Collection") class has been added for representing [`collections.abc.Collection`](../library/collections.abc.xhtml#collections.abc.Collection "collections.abc.Collection"). (Contributed by Ivan Levkivskyi in [bpo-27598](https://bugs.python.org/issue27598) \[https://bugs.python.org/issue27598\].) The [`typing.ClassVar`](../library/typing.xhtml#typing.ClassVar "typing.ClassVar") type construct has been added to mark class variables. As introduced in [**PEP 526**](https://www.python.org/dev/peps/pep-0526) \[https://www.python.org/dev/peps/pep-0526\], a variable annotation wrapped in ClassVar indicates that a given attribute is intended to be used as a class variable and should not be set on instances of that class. (Contributed by Ivan Levkivskyi in [Github #280](https://github.com/python/typing/pull/280) \[https://github.com/python/typing/pull/280\].) A new [`TYPE_CHECKING`](../library/typing.xhtml#typing.TYPE_CHECKING "typing.TYPE_CHECKING") constant that is assumed to be `True` by the static type checkers, but is `False` at runtime. (Contributed by Guido van Rossum in [Github #230](https://github.com/python/typing/issues/230) \[https://github.com/python/typing/issues/230\].) A new [`NewType()`](../library/typing.xhtml#typing.NewType "typing.NewType") helper function has been added to create lightweight distinct types for annotations: ``` from typing import NewType UserId = NewType('UserId', int) some_id = UserId(524313) ``` The static type checker will treat the new type as if it were a subclass of the original type. (Contributed by Ivan Levkivskyi in [Github #189](https://github.com/python/typing/issues/189) \[https://github.com/python/typing/issues/189\].) ### unicodedata The [`unicodedata`](../library/unicodedata.xhtml#module-unicodedata "unicodedata: Access the Unicode Database.") module now uses data from [Unicode 9.0.0](http://unicode.org/versions/Unicode9.0.0/) \[http://unicode.org/versions/Unicode9.0.0/\]. (Contributed by Benjamin Peterson.) ### unittest.mock The [`Mock`](../library/unittest.mock.xhtml#unittest.mock.Mock "unittest.mock.Mock") class has the following improvements: - Two new methods, [`Mock.assert_called()`](../library/unittest.mock.xhtml#unittest.mock.Mock.assert_called "unittest.mock.Mock.assert_called") and [`Mock.assert_called_once()`](../library/unittest.mock.xhtml#unittest.mock.Mock.assert_called_once "unittest.mock.Mock.assert_called_once") to check if the mock object was called. (Contributed by Amit Saha in [bpo-26323](https://bugs.python.org/issue26323) \[https://bugs.python.org/issue26323\].) - The [`Mock.reset_mock()`](../library/unittest.mock.xhtml#unittest.mock.Mock.reset_mock "unittest.mock.Mock.reset_mock") method now has two optional keyword only arguments: *return\_value* and *side\_effect*. (Contributed by Kushal Das in [bpo-21271](https://bugs.python.org/issue21271) \[https://bugs.python.org/issue21271\].) ### urllib.request If a HTTP request has a file or iterable body (other than a bytes object) but no `Content-Length` header, rather than throwing an error, `AbstractHTTPHandler` now falls back to use chunked transfer encoding. (Contributed by Demian Brecht and Rolf Krahl in [bpo-12319](https://bugs.python.org/issue12319) \[https://bugs.python.org/issue12319\].) ### urllib.robotparser [`RobotFileParser`](../library/urllib.robotparser.xhtml#urllib.robotparser.RobotFileParser "urllib.robotparser.RobotFileParser") now supports the `Crawl-delay` and `Request-rate` extensions. (Contributed by Nikolay Bogoychev in [bpo-16099](https://bugs.python.org/issue16099) \[https://bugs.python.org/issue16099\].) ### venv [`venv`](../library/venv.xhtml#module-venv "venv: Creation of virtual environments.") accepts a new parameter `--prompt`. This parameter provides an alternative prefix for the virtual environment. (Proposed by Łukasz Balcerzak and ported to 3.6 by Stéphane Wirtel in [bpo-22829](https://bugs.python.org/issue22829) \[https://bugs.python.org/issue22829\].) ### warnings A new optional *source* parameter has been added to the [`warnings.warn_explicit()`](../library/warnings.xhtml#warnings.warn_explicit "warnings.warn_explicit") function: the destroyed object which emitted a [`ResourceWarning`](../library/exceptions.xhtml#ResourceWarning "ResourceWarning"). A *source* attribute has also been added to `warnings.WarningMessage` (contributed by Victor Stinner in [bpo-26568](https://bugs.python.org/issue26568) \[https://bugs.python.org/issue26568\] and [bpo-26567](https://bugs.python.org/issue26567) \[https://bugs.python.org/issue26567\]). When a [`ResourceWarning`](../library/exceptions.xhtml#ResourceWarning "ResourceWarning") warning is logged, the [`tracemalloc`](../library/tracemalloc.xhtml#module-tracemalloc "tracemalloc: Trace memory allocations.") module is now used to try to retrieve the traceback where the destroyed object was allocated. Example with the script `example.py`: ``` import warnings def func(): return open(__file__) f = func() f = None ``` Output of the command `python3.6 -Wd -X tracemalloc=5 example.py`: ``` example.py:7: ResourceWarning: unclosed file <_io.TextIOWrapper name='example.py' mode='r' encoding='UTF-8'> f = None Object allocated at (most recent call first): File "example.py", lineno 4 return open(__file__) File "example.py", lineno 6 f = func() ``` The "Object allocated at" traceback is new and is only displayed if [`tracemalloc`](../library/tracemalloc.xhtml#module-tracemalloc "tracemalloc: Trace memory allocations.") is tracing Python memory allocations and if the [`warnings`](../library/warnings.xhtml#module-warnings "warnings: Issue warning messages and control their disposition.") module was already imported. ### winreg Added the 64-bit integer type [`REG_QWORD`](../library/winreg.xhtml#winreg.REG_QWORD "winreg.REG_QWORD"). (Contributed by Clement Rouault in [bpo-23026](https://bugs.python.org/issue23026) \[https://bugs.python.org/issue23026\].) ### winsound Allowed keyword arguments to be passed to [`Beep`](../library/winsound.xhtml#winsound.Beep "winsound.Beep"), [`MessageBeep`](../library/winsound.xhtml#winsound.MessageBeep "winsound.MessageBeep"), and [`PlaySound`](../library/winsound.xhtml#winsound.PlaySound "winsound.PlaySound") ([bpo-27982](https://bugs.python.org/issue27982) \[https://bugs.python.org/issue27982\]). ### xmlrpc.client The [`xmlrpc.client`](../library/xmlrpc.client.xhtml#module-xmlrpc.client "xmlrpc.client: XML-RPC client access.") module now supports unmarshalling additional data types used by the Apache XML-RPC implementation for numerics and `None`. (Contributed by Serhiy Storchaka in [bpo-26885](https://bugs.python.org/issue26885) \[https://bugs.python.org/issue26885\].) ### zipfile A new [`ZipInfo.from_file()`](../library/zipfile.xhtml#zipfile.ZipInfo.from_file "zipfile.ZipInfo.from_file") class method allows making a [`ZipInfo`](../library/zipfile.xhtml#zipfile.ZipInfo "zipfile.ZipInfo") instance from a filesystem file. A new [`ZipInfo.is_dir()`](../library/zipfile.xhtml#zipfile.ZipInfo.is_dir "zipfile.ZipInfo.is_dir") method can be used to check if the [`ZipInfo`](../library/zipfile.xhtml#zipfile.ZipInfo "zipfile.ZipInfo") instance represents a directory. (Contributed by Thomas Kluyver in [bpo-26039](https://bugs.python.org/issue26039) \[https://bugs.python.org/issue26039\].) The [`ZipFile.open()`](../library/zipfile.xhtml#zipfile.ZipFile.open "zipfile.ZipFile.open") method can now be used to write data into a ZIP file, as well as for extracting data. (Contributed by Thomas Kluyver in [bpo-26039](https://bugs.python.org/issue26039) \[https://bugs.python.org/issue26039\].) ### zlib The [`compress()`](../library/zlib.xhtml#zlib.compress "zlib.compress") and [`decompress()`](../library/zlib.xhtml#zlib.decompress "zlib.decompress") functions now accept keyword arguments. (Contributed by Aviv Palivoda in [bpo-26243](https://bugs.python.org/issue26243) \[https://bugs.python.org/issue26243\] and Xiang Zhang in [bpo-16764](https://bugs.python.org/issue16764) \[https://bugs.python.org/issue16764\] respectively.) ## 性能优化 - The Python interpreter now uses a 16-bit wordcode instead of bytecode which made a number of opcode optimizations possible. (Contributed by Demur Rumed with input and reviews from Serhiy Storchaka and Victor Stinner in [bpo-26647](https://bugs.python.org/issue26647) \[https://bugs.python.org/issue26647\] and [bpo-28050](https://bugs.python.org/issue28050) \[https://bugs.python.org/issue28050\].) - The [`asyncio.Future`](../library/asyncio-future.xhtml#asyncio.Future "asyncio.Future") class now has an optimized C implementation. (Contributed by Yury Selivanov and INADA Naoki in [bpo-26081](https://bugs.python.org/issue26081) \[https://bugs.python.org/issue26081\].) - The [`asyncio.Task`](../library/asyncio-task.xhtml#asyncio.Task "asyncio.Task") class now has an optimized C implementation. (Contributed by Yury Selivanov in [bpo-28544](https://bugs.python.org/issue28544) \[https://bugs.python.org/issue28544\].) - Various implementation improvements in the [`typing`](../library/typing.xhtml#module-typing "typing: Support for type hints (see PEP 484).") module (such as caching of generic types) allow up to 30 times performance improvements and reduced memory footprint. - The ASCII decoder is now up to 60 times as fast for error handlers `surrogateescape`, `ignore` and `replace` (Contributed by Victor Stinner in [bpo-24870](https://bugs.python.org/issue24870) \[https://bugs.python.org/issue24870\]). - The ASCII and the Latin1 encoders are now up to 3 times as fast for the error handler `surrogateescape`(Contributed by Victor Stinner in [bpo-25227](https://bugs.python.org/issue25227) \[https://bugs.python.org/issue25227\]). - The UTF-8 encoder is now up to 75 times as fast for error handlers `ignore`, `replace`, `surrogateescape`, `surrogatepass` (Contributed by Victor Stinner in [bpo-25267](https://bugs.python.org/issue25267) \[https://bugs.python.org/issue25267\]). - The UTF-8 decoder is now up to 15 times as fast for error handlers `ignore`, `replace` and `surrogateescape` (Contributed by Victor Stinner in [bpo-25301](https://bugs.python.org/issue25301) \[https://bugs.python.org/issue25301\]). - `bytes % args` is now up to 2 times faster. (Contributed by Victor Stinner in [bpo-25349](https://bugs.python.org/issue25349) \[https://bugs.python.org/issue25349\]). - `bytearray % args` is now between 2.5 and 5 times faster. (Contributed by Victor Stinner in [bpo-25399](https://bugs.python.org/issue25399) \[https://bugs.python.org/issue25399\]). - Optimize [`bytes.fromhex()`](../library/stdtypes.xhtml#bytes.fromhex "bytes.fromhex") and [`bytearray.fromhex()`](../library/stdtypes.xhtml#bytearray.fromhex "bytearray.fromhex"): they are now between 2x and 3.5x faster. (Contributed by Victor Stinner in [bpo-25401](https://bugs.python.org/issue25401) \[https://bugs.python.org/issue25401\]). - Optimize `bytes.replace(b'', b'.')` and `bytearray.replace(b'', b'.')`: up to 80% faster. (Contributed by Josh Snider in [bpo-26574](https://bugs.python.org/issue26574) \[https://bugs.python.org/issue26574\]). - Allocator functions of the [`PyMem_Malloc()`](../c-api/memory.xhtml#c.PyMem_Malloc "PyMem_Malloc") domain ([`PYMEM_DOMAIN_MEM`](../c-api/memory.xhtml#c.PYMEM_DOMAIN_MEM "PYMEM_DOMAIN_MEM")) now use the [pymalloc memory allocator](../c-api/memory.xhtml#pymalloc) instead of `malloc()` function of the C library. The pymalloc allocator is optimized for objects smaller or equal to 512 bytes with a short lifetime, and use `malloc()` for larger memory blocks. (Contributed by Victor Stinner in [bpo-26249](https://bugs.python.org/issue26249) \[https://bugs.python.org/issue26249\]). - [`pickle.load()`](../library/pickle.xhtml#pickle.load "pickle.load") and [`pickle.loads()`](../library/pickle.xhtml#pickle.loads "pickle.loads") are now up to 10% faster when deserializing many small objects (Contributed by Victor Stinner in [bpo-27056](https://bugs.python.org/issue27056) \[https://bugs.python.org/issue27056\]). - Passing [keyword arguments](../glossary.xhtml#term-keyword-argument) to a function has an overhead in comparison with passing [positional arguments](../glossary.xhtml#term-positional-argument). Now in extension functions implemented with using Argument Clinic this overhead is significantly decreased. (Contributed by Serhiy Storchaka in [bpo-27574](https://bugs.python.org/issue27574) \[https://bugs.python.org/issue27574\]). - Optimized [`glob()`](../library/glob.xhtml#glob.glob "glob.glob") and [`iglob()`](../library/glob.xhtml#glob.iglob "glob.iglob") functions in the [`glob`](../library/glob.xhtml#module-glob "glob: Unix shell style pathname pattern expansion.") module; they are now about 3--6 times faster. (Contributed by Serhiy Storchaka in [bpo-25596](https://bugs.python.org/issue25596) \[https://bugs.python.org/issue25596\]). - Optimized globbing in [`pathlib`](../library/pathlib.xhtml#module-pathlib "pathlib: Object-oriented filesystem paths") by using [`os.scandir()`](../library/os.xhtml#os.scandir "os.scandir"); it is now about 1.5--4 times faster. (Contributed by Serhiy Storchaka in [bpo-26032](https://bugs.python.org/issue26032) \[https://bugs.python.org/issue26032\]). - [`xml.etree.ElementTree`](../library/xml.etree.elementtree.xhtml#module-xml.etree.ElementTree "xml.etree.ElementTree: Implementation of the ElementTree API.") parsing, iteration and deepcopy performance has been significantly improved. (Contributed by Serhiy Storchaka in [bpo-25638](https://bugs.python.org/issue25638) \[https://bugs.python.org/issue25638\], [bpo-25873](https://bugs.python.org/issue25873) \[https://bugs.python.org/issue25873\], and [bpo-25869](https://bugs.python.org/issue25869) \[https://bugs.python.org/issue25869\].) - Creation of [`fractions.Fraction`](../library/fractions.xhtml#fractions.Fraction "fractions.Fraction") instances from floats and decimals is now 2 to 3 times faster. (Contributed by Serhiy Storchaka in [bpo-25971](https://bugs.python.org/issue25971) \[https://bugs.python.org/issue25971\].) ## Build and C API Changes - Python now requires some C99 support in the toolchain to build. Most notably, Python now uses standard integer types and macros in place of custom macros like `PY_LONG_LONG`. For more information, see [**PEP 7**](https://www.python.org/dev/peps/pep-0007) \[https://www.python.org/dev/peps/pep-0007\] and [bpo-17884](https://bugs.python.org/issue17884) \[https://bugs.python.org/issue17884\]. - Cross-compiling CPython with the Android NDK and the Android API level set to 21 (Android 5.0 Lollipop) or greater runs successfully. While Android is not yet a supported platform, the Python test suite runs on the Android emulator with only about 16 tests failures. See the Android meta-issue [bpo-26865](https://bugs.python.org/issue26865) \[https://bugs.python.org/issue26865\]. - The `--enable-optimizations` configure flag has been added. Turning it on will activate expensive optimizations like PGO. (Original patch by Alecsandru Patrascu of Intel in [bpo-26359](https://bugs.python.org/issue26359) \[https://bugs.python.org/issue26359\].) - The [GIL](../glossary.xhtml#term-global-interpreter-lock) must now be held when allocator functions of [`PYMEM_DOMAIN_OBJ`](../c-api/memory.xhtml#c.PYMEM_DOMAIN_OBJ "PYMEM_DOMAIN_OBJ") (ex: [`PyObject_Malloc()`](../c-api/memory.xhtml#c.PyObject_Malloc "PyObject_Malloc")) and [`PYMEM_DOMAIN_MEM`](../c-api/memory.xhtml#c.PYMEM_DOMAIN_MEM "PYMEM_DOMAIN_MEM") (ex: [`PyMem_Malloc()`](../c-api/memory.xhtml#c.PyMem_Malloc "PyMem_Malloc")) domains are called. - New [`Py_FinalizeEx()`](../c-api/init.xhtml#c.Py_FinalizeEx "Py_FinalizeEx") API which indicates if flushing buffered data failed. (Contributed by Martin Panter in [bpo-5319](https://bugs.python.org/issue5319) \[https://bugs.python.org/issue5319\].) - [`PyArg_ParseTupleAndKeywords()`](../c-api/arg.xhtml#c.PyArg_ParseTupleAndKeywords "PyArg_ParseTupleAndKeywords") now supports [positional-only parameters](../glossary.xhtml#positional-only-parameter). Positional-only parameters are defined by empty names. (Contributed by Serhiy Storchaka in [bpo-26282](https://bugs.python.org/issue26282) \[https://bugs.python.org/issue26282\]). - `PyTraceback_Print` method now abbreviates long sequences of repeated lines as `"[Previous line repeated {count} more times]"`. (Contributed by Emanuel Barry in [bpo-26823](https://bugs.python.org/issue26823) \[https://bugs.python.org/issue26823\].) - The new [`PyErr_SetImportErrorSubclass()`](../c-api/exceptions.xhtml#c.PyErr_SetImportErrorSubclass "PyErr_SetImportErrorSubclass") function allows for specifying a subclass of [`ImportError`](../library/exceptions.xhtml#ImportError "ImportError") to raise. (Contributed by Eric Snow in [bpo-15767](https://bugs.python.org/issue15767) \[https://bugs.python.org/issue15767\].) - The new [`PyErr_ResourceWarning()`](../c-api/exceptions.xhtml#c.PyErr_ResourceWarning "PyErr_ResourceWarning") function can be used to generate a [`ResourceWarning`](../library/exceptions.xhtml#ResourceWarning "ResourceWarning") providing the source of the resource allocation. (Contributed by Victor Stinner in [bpo-26567](https://bugs.python.org/issue26567) \[https://bugs.python.org/issue26567\].) - The new [`PyOS_FSPath()`](../c-api/sys.xhtml#c.PyOS_FSPath "PyOS_FSPath") function returns the file system representation of a [path-like object](../glossary.xhtml#term-path-like-object). (Contributed by Brett Cannon in [bpo-27186](https://bugs.python.org/issue27186) \[https://bugs.python.org/issue27186\].) - The [`PyUnicode_FSConverter()`](../c-api/unicode.xhtml#c.PyUnicode_FSConverter "PyUnicode_FSConverter") and [`PyUnicode_FSDecoder()`](../c-api/unicode.xhtml#c.PyUnicode_FSDecoder "PyUnicode_FSDecoder")functions will now accept [path-like objects](../glossary.xhtml#term-path-like-object). ## 其他改进 - When [`--version`](../using/cmdline.xhtml#cmdoption-version) (short form: [`-V`](../using/cmdline.xhtml#cmdoption-v)) is supplied twice, Python prints [`sys.version`](../library/sys.xhtml#sys.version "sys.version") for detailed information. ``` $ ./python -VV Python 3.6.0b4+ (3.6:223967b49e49+, Nov 21 2016, 20:55:04) [GCC 4.2.1 Compatible Apple LLVM 8.0.0 (clang-800.0.42.1)] ``` ## 弃用 ### New Keywords `async` and `await` are not recommended to be used as variable, class, function or module names. Introduced by [**PEP 492**](https://www.python.org/dev/peps/pep-0492) \[https://www.python.org/dev/peps/pep-0492\] in Python 3.5, they will become proper keywords in Python 3.7. Starting in Python 3.6, the use of `async` or `await` as names will generate a [`DeprecationWarning`](../library/exceptions.xhtml#DeprecationWarning "DeprecationWarning"). ### 已弃用的 Python 行为 Raising the [`StopIteration`](../library/exceptions.xhtml#StopIteration "StopIteration") exception inside a generator will now generate a [`DeprecationWarning`](../library/exceptions.xhtml#DeprecationWarning "DeprecationWarning"), and will trigger a [`RuntimeError`](../library/exceptions.xhtml#RuntimeError "RuntimeError")in Python 3.7. See [PEP 479: Change StopIteration handling inside generators](3.5.xhtml#whatsnew-pep-479) for details. The [`__aiter__()`](../reference/datamodel.xhtml#object.__aiter__ "object.__aiter__") method is now expected to return an asynchronous iterator directly instead of returning an awaitable as previously. Doing the former will trigger a [`DeprecationWarning`](../library/exceptions.xhtml#DeprecationWarning "DeprecationWarning"). Backward compatibility will be removed in Python 3.7. (Contributed by Yury Selivanov in [bpo-27243](https://bugs.python.org/issue27243) \[https://bugs.python.org/issue27243\].) A backslash-character pair that is not a valid escape sequence now generates a [`DeprecationWarning`](../library/exceptions.xhtml#DeprecationWarning "DeprecationWarning"). Although this will eventually become a [`SyntaxError`](../library/exceptions.xhtml#SyntaxError "SyntaxError"), that will not be for several Python releases. (Contributed by Emanuel Barry in [bpo-27364](https://bugs.python.org/issue27364) \[https://bugs.python.org/issue27364\].) When performing a relative import, falling back on `__name__` and `__path__` from the calling module when `__spec__` or `__package__` are not defined now raises an [`ImportWarning`](../library/exceptions.xhtml#ImportWarning "ImportWarning"). (Contributed by Rose Ames in [bpo-25791](https://bugs.python.org/issue25791) \[https://bugs.python.org/issue25791\].) ### 已弃用的 Python 模块、函数和方法 #### asynchat The [`asynchat`](../library/asynchat.xhtml#module-asynchat "asynchat: Support for asynchronous command/response protocols.") has been deprecated in favor of [`asyncio`](../library/asyncio.xhtml#module-asyncio "asyncio: Asynchronous I/O."). (Contributed by Mariatta in [bpo-25002](https://bugs.python.org/issue25002) \[https://bugs.python.org/issue25002\].) #### asyncore The [`asyncore`](../library/asyncore.xhtml#module-asyncore "asyncore: A base class for developing asynchronous socket handling services.") has been deprecated in favor of [`asyncio`](../library/asyncio.xhtml#module-asyncio "asyncio: Asynchronous I/O."). (Contributed by Mariatta in [bpo-25002](https://bugs.python.org/issue25002) \[https://bugs.python.org/issue25002\].) #### dbm Unlike other [`dbm`](../library/dbm.xhtml#module-dbm "dbm: Interfaces to various Unix "database" formats.") implementations, the [`dbm.dumb`](../library/dbm.xhtml#module-dbm.dumb "dbm.dumb: Portable implementation of the simple DBM interface.") module creates databases with the `'rw'` mode and allows modifying the database opened with the `'r'` mode. This behavior is now deprecated and will be removed in 3.8. (Contributed by Serhiy Storchaka in [bpo-21708](https://bugs.python.org/issue21708) \[https://bugs.python.org/issue21708\].) #### distutils The undocumented `extra_path` argument to the `Distribution` constructor is now considered deprecated and will raise a warning if set. Support for this parameter will be removed in a future Python release. See [bpo-27919](https://bugs.python.org/issue27919) \[https://bugs.python.org/issue27919\] for details. #### grp The support of non-integer arguments in [`getgrgid()`](../library/grp.xhtml#grp.getgrgid "grp.getgrgid") has been deprecated. (Contributed by Serhiy Storchaka in [bpo-26129](https://bugs.python.org/issue26129) \[https://bugs.python.org/issue26129\].) #### importlib The [`importlib.machinery.SourceFileLoader.load_module()`](../library/importlib.xhtml#importlib.machinery.SourceFileLoader.load_module "importlib.machinery.SourceFileLoader.load_module") and [`importlib.machinery.SourcelessFileLoader.load_module()`](../library/importlib.xhtml#importlib.machinery.SourcelessFileLoader.load_module "importlib.machinery.SourcelessFileLoader.load_module") methods are now deprecated. They were the only remaining implementations of [`importlib.abc.Loader.load_module()`](../library/importlib.xhtml#importlib.abc.Loader.load_module "importlib.abc.Loader.load_module") in [`importlib`](../library/importlib.xhtml#module-importlib "importlib: The implementation of the import machinery.") that had not been deprecated in previous versions of Python in favour of [`importlib.abc.Loader.exec_module()`](../library/importlib.xhtml#importlib.abc.Loader.exec_module "importlib.abc.Loader.exec_module"). The [`importlib.machinery.WindowsRegistryFinder`](../library/importlib.xhtml#importlib.machinery.WindowsRegistryFinder "importlib.machinery.WindowsRegistryFinder") class is now deprecated. As of 3.6.0, it is still added to [`sys.meta_path`](../library/sys.xhtml#sys.meta_path "sys.meta_path") by default (on Windows), but this may change in future releases. #### os Undocumented support of general [bytes-like objects](../glossary.xhtml#term-bytes-like-object)as paths in [`os`](../library/os.xhtml#module-os "os: Miscellaneous operating system interfaces.") functions, [`compile()`](../library/functions.xhtml#compile "compile") and similar functions is now deprecated. (Contributed by Serhiy Storchaka in [bpo-25791](https://bugs.python.org/issue25791) \[https://bugs.python.org/issue25791\] and [bpo-26754](https://bugs.python.org/issue26754) \[https://bugs.python.org/issue26754\].) #### re Support for inline flags `(?letters)` in the middle of the regular expression has been deprecated and will be removed in a future Python version. Flags at the start of a regular expression are still allowed. (Contributed by Serhiy Storchaka in [bpo-22493](https://bugs.python.org/issue22493) \[https://bugs.python.org/issue22493\].) #### ssl OpenSSL 0.9.8, 1.0.0 and 1.0.1 are deprecated and no longer supported. In the future the [`ssl`](../library/ssl.xhtml#module-ssl "ssl: TLS/SSL wrapper for socket objects") module will require at least OpenSSL 1.0.2 or 1.1.0. SSL-related arguments like `certfile`, `keyfile` and `check_hostname`in [`ftplib`](../library/ftplib.xhtml#module-ftplib "ftplib: FTP protocol client (requires sockets)."), [`http.client`](../library/http.client.xhtml#module-http.client "http.client: HTTP and HTTPS protocol client (requires sockets)."), [`imaplib`](../library/imaplib.xhtml#module-imaplib "imaplib: IMAP4 protocol client (requires sockets)."), [`poplib`](../library/poplib.xhtml#module-poplib "poplib: POP3 protocol client (requires sockets)."), and [`smtplib`](../library/smtplib.xhtml#module-smtplib "smtplib: SMTP protocol client (requires sockets).") have been deprecated in favor of `context`. (Contributed by Christian Heimes in [bpo-28022](https://bugs.python.org/issue28022) \[https://bugs.python.org/issue28022\].) A couple of protocols and functions of the [`ssl`](../library/ssl.xhtml#module-ssl "ssl: TLS/SSL wrapper for socket objects") module are now deprecated. Some features will no longer be available in future versions of OpenSSL. Other features are deprecated in favor of a different API. (Contributed by Christian Heimes in [bpo-28022](https://bugs.python.org/issue28022) \[https://bugs.python.org/issue28022\] and [bpo-26470](https://bugs.python.org/issue26470) \[https://bugs.python.org/issue26470\].) #### tkinter The [`tkinter.tix`](../library/tkinter.tix.xhtml#module-tkinter.tix "tkinter.tix: Tk Extension Widgets for Tkinter") module is now deprecated. [`tkinter`](../library/tkinter.xhtml#module-tkinter "tkinter: Interface to Tcl/Tk for graphical user interfaces") users should use [`tkinter.ttk`](../library/tkinter.ttk.xhtml#module-tkinter.ttk "tkinter.ttk: Tk themed widget set") instead. #### venv The `pyvenv` script has been deprecated in favour of `python3 -m venv`. This prevents confusion as to what Python interpreter `pyvenv` is connected to and thus what Python interpreter will be used by the virtual environment. (Contributed by Brett Cannon in [bpo-25154](https://bugs.python.org/issue25154) \[https://bugs.python.org/issue25154\].) ### 已弃用的 C API 函数和类型 Undocumented functions `PyUnicode_AsEncodedObject()`, `PyUnicode_AsDecodedObject()`, `PyUnicode_AsEncodedUnicode()`and `PyUnicode_AsDecodedUnicode()` are deprecated now. Use the [generic codec based API](../c-api/codec.xhtml#codec-registry) instead. ### Deprecated Build Options The `--with-system-ffi` configure flag is now on by default on non-macOS UNIX platforms. It may be disabled by using `--without-system-ffi`, but using the flag is deprecated and will not be accepted in Python 3.7. macOS is unaffected by this change. Note that many OS distributors already use the `--with-system-ffi` flag when building their system Python. ## 移除 ### API 与特性的移除 - Unknown escapes consisting of `'\'` and an ASCII letter in regular expressions will now cause an error. In replacement templates for [`re.sub()`](../library/re.xhtml#re.sub "re.sub") they are still allowed, but deprecated. The [`re.LOCALE`](../library/re.xhtml#re.LOCALE "re.LOCALE") flag can now only be used with binary patterns. - `inspect.getmoduleinfo()` was removed (was deprecated since CPython 3.3). [`inspect.getmodulename()`](../library/inspect.xhtml#inspect.getmodulename "inspect.getmodulename") should be used for obtaining the module name for a given path. (Contributed by Yury Selivanov in [bpo-13248](https://bugs.python.org/issue13248) \[https://bugs.python.org/issue13248\].) - `traceback.Ignore` class and `traceback.usage`, `traceback.modname`, `traceback.fullmodname`, `traceback.find_lines_from_code`, `traceback.find_lines`, `traceback.find_strings`, `traceback.find_executable_lines` methods were removed from the [`traceback`](../library/traceback.xhtml#module-traceback "traceback: Print or retrieve a stack traceback.") module. They were undocumented methods deprecated since Python 3.2 and equivalent functionality is available from private methods. - The `tk_menuBar()` and `tk_bindForTraversal()` dummy methods in [`tkinter`](../library/tkinter.xhtml#module-tkinter "tkinter: Interface to Tcl/Tk for graphical user interfaces") widget classes were removed (corresponding Tk commands were obsolete since Tk 4.0). - The [`open()`](../library/zipfile.xhtml#zipfile.ZipFile.open "zipfile.ZipFile.open") method of the [`zipfile.ZipFile`](../library/zipfile.xhtml#zipfile.ZipFile "zipfile.ZipFile")class no longer supports the `'U'` mode (was deprecated since Python 3.4). Use [`io.TextIOWrapper`](../library/io.xhtml#io.TextIOWrapper "io.TextIOWrapper") for reading compressed text files in [universal newlines](../glossary.xhtml#term-universal-newlines) mode. - The undocumented `IN`, `CDROM`, `DLFCN`, `TYPES`, `CDIO`, and `STROPTS` modules have been removed. They had been available in the platform specific `Lib/plat-*/` directories, but were chronically out of date, inconsistently available across platforms, and unmaintained. The script that created these modules is still available in the source distribution at [Tools/scripts/h2py.py](https://github.com/python/cpython/tree/3.7/Tools/scripts/h2py.py) \[https://github.com/python/cpython/tree/3.7/Tools/scripts/h2py.py\]. - The deprecated `asynchat.fifo` class has been removed. ## 移植到Python 3.6 本节列出了先前描述的更改以及可能需要更改代码的其他错误修正. ### 'python' 命令行为的变化 - The output of a special Python build with defined `COUNT_ALLOCS`, `SHOW_ALLOC_COUNT` or `SHOW_TRACK_COUNT` macros is now off by default. It can be re-enabled using the `-X showalloccount` option. It now outputs to `stderr` instead of `stdout`. (Contributed by Serhiy Storchaka in [bpo-23034](https://bugs.python.org/issue23034) \[https://bugs.python.org/issue23034\].) ### 改变了的Python API - [`open()`](../library/functions.xhtml#open "open") will no longer allow combining the `'U'` mode flag with `'+'`. (Contributed by Jeff Balogh and John O'Connor in [bpo-2091](https://bugs.python.org/issue2091) \[https://bugs.python.org/issue2091\].) - [`sqlite3`](../library/sqlite3.xhtml#module-sqlite3 "sqlite3: A DB-API 2.0 implementation using SQLite 3.x.") no longer implicitly commits an open transaction before DDL statements. - On Linux, [`os.urandom()`](../library/os.xhtml#os.urandom "os.urandom") now blocks until the system urandom entropy pool is initialized to increase the security. - When [`importlib.abc.Loader.exec_module()`](../library/importlib.xhtml#importlib.abc.Loader.exec_module "importlib.abc.Loader.exec_module") is defined, [`importlib.abc.Loader.create_module()`](../library/importlib.xhtml#importlib.abc.Loader.create_module "importlib.abc.Loader.create_module") must also be defined. - [`PyErr_SetImportError()`](../c-api/exceptions.xhtml#c.PyErr_SetImportError "PyErr_SetImportError") now sets [`TypeError`](../library/exceptions.xhtml#TypeError "TypeError") when its **msg**argument is not set. Previously only `NULL` was returned. - The format of the `co_lnotab` attribute of code objects changed to support a negative line number delta. By default, Python does not emit bytecode with a negative line number delta. Functions using `frame.f_lineno`, `PyFrame_GetLineNumber()` or `PyCode_Addr2Line()` are not affected. Functions directly decoding `co_lnotab` should be updated to use a signed 8-bit integer type for the line number delta, but this is only required to support applications using a negative line number delta. See `Objects/lnotab_notes.txt` for the `co_lnotab` format and how to decode it, and see the [**PEP 511**](https://www.python.org/dev/peps/pep-0511) \[https://www.python.org/dev/peps/pep-0511\] for the rationale. - The functions in the [`compileall`](../library/compileall.xhtml#module-compileall "compileall: Tools for byte-compiling all Python source files in a directory tree.") module now return booleans instead of `1` or `0` to represent success or failure, respectively. Thanks to booleans being a subclass of integers, this should only be an issue if you were doing identity checks for `1` or `0`. See [bpo-25768](https://bugs.python.org/issue25768) \[https://bugs.python.org/issue25768\]. - Reading the `port` attribute of [`urllib.parse.urlsplit()`](../library/urllib.parse.xhtml#urllib.parse.urlsplit "urllib.parse.urlsplit") and [`urlparse()`](../library/urllib.parse.xhtml#urllib.parse.urlparse "urllib.parse.urlparse") results now raises [`ValueError`](../library/exceptions.xhtml#ValueError "ValueError") for out-of-range values, rather than returning [`None`](../library/constants.xhtml#None "None"). See [bpo-20059](https://bugs.python.org/issue20059) \[https://bugs.python.org/issue20059\]. - The [`imp`](../library/imp.xhtml#module-imp "imp: Access the implementation of the import statement. (已移除)") module now raises a [`DeprecationWarning`](../library/exceptions.xhtml#DeprecationWarning "DeprecationWarning") instead of [`PendingDeprecationWarning`](../library/exceptions.xhtml#PendingDeprecationWarning "PendingDeprecationWarning"). - The following modules have had missing APIs added to their `__all__`attributes to match the documented APIs: [`calendar`](../library/calendar.xhtml#module-calendar "calendar: Functions for working with calendars, including some emulation of the Unix cal program."), [`cgi`](../library/cgi.xhtml#module-cgi "cgi: Helpers for running Python scripts via the Common Gateway Interface."), [`csv`](../library/csv.xhtml#module-csv "csv: Write and read tabular data to and from delimited files."), [`ElementTree`](../library/xml.etree.elementtree.xhtml#module-xml.etree.ElementTree "xml.etree.ElementTree: Implementation of the ElementTree API."), [`enum`](../library/enum.xhtml#module-enum "enum: Implementation of an enumeration class."), [`fileinput`](../library/fileinput.xhtml#module-fileinput "fileinput: Loop over standard input or a list of files."), [`ftplib`](../library/ftplib.xhtml#module-ftplib "ftplib: FTP protocol client (requires sockets)."), [`logging`](../library/logging.xhtml#module-logging "logging: Flexible event logging system for applications."), [`mailbox`](../library/mailbox.xhtml#module-mailbox "mailbox: Manipulate mailboxes in various formats"), [`mimetypes`](../library/mimetypes.xhtml#module-mimetypes "mimetypes: Mapping of filename extensions to MIME types."), [`optparse`](../library/optparse.xhtml#module-optparse "optparse: Command-line option parsing library. (已移除)"), [`plistlib`](../library/plistlib.xhtml#module-plistlib "plistlib: Generate and parse Mac OS X plist files."), [`smtpd`](../library/smtpd.xhtml#module-smtpd "smtpd: A SMTP server implementation in Python."), [`subprocess`](../library/subprocess.xhtml#module-subprocess "subprocess: Subprocess management."), [`tarfile`](../library/tarfile.xhtml#module-tarfile "tarfile: Read and write tar-format archive files."), [`threading`](../library/threading.xhtml#module-threading "threading: Thread-based parallelism.") and [`wave`](../library/wave.xhtml#module-wave "wave: Provide an interface to the WAV sound format."). This means they will export new symbols when `import *`is used. (Contributed by Joel Taddei and Jacek Kołodziej in [bpo-23883](https://bugs.python.org/issue23883) \[https://bugs.python.org/issue23883\].) - When performing a relative import, if `__package__` does not compare equal to `__spec__.parent` then [`ImportWarning`](../library/exceptions.xhtml#ImportWarning "ImportWarning") is raised. (Contributed by Brett Cannon in [bpo-25791](https://bugs.python.org/issue25791) \[https://bugs.python.org/issue25791\].) - When a relative import is performed and no parent package is known, then [`ImportError`](../library/exceptions.xhtml#ImportError "ImportError") will be raised. Previously, [`SystemError`](../library/exceptions.xhtml#SystemError "SystemError") could be raised. (Contributed by Brett Cannon in [bpo-18018](https://bugs.python.org/issue18018) \[https://bugs.python.org/issue18018\].) - Servers based on the [`socketserver`](../library/socketserver.xhtml#module-socketserver "socketserver: A framework for network servers.") module, including those defined in [`http.server`](../library/http.server.xhtml#module-http.server "http.server: HTTP server and request handlers."), [`xmlrpc.server`](../library/xmlrpc.server.xhtml#module-xmlrpc.server "xmlrpc.server: Basic XML-RPC server implementations.") and [`wsgiref.simple_server`](../library/wsgiref.xhtml#module-wsgiref.simple_server "wsgiref.simple_server: A simple WSGI HTTP server."), now only catch exceptions derived from [`Exception`](../library/exceptions.xhtml#Exception "Exception"). Therefore if a request handler raises an exception like [`SystemExit`](../library/exceptions.xhtml#SystemExit "SystemExit") or [`KeyboardInterrupt`](../library/exceptions.xhtml#KeyboardInterrupt "KeyboardInterrupt"), [`handle_error()`](../library/socketserver.xhtml#socketserver.BaseServer.handle_error "socketserver.BaseServer.handle_error") is no longer called, and the exception will stop a single-threaded server. (Contributed by Martin Panter in [bpo-23430](https://bugs.python.org/issue23430) \[https://bugs.python.org/issue23430\].) - [`spwd.getspnam()`](../library/spwd.xhtml#spwd.getspnam "spwd.getspnam") now raises a [`PermissionError`](../library/exceptions.xhtml#PermissionError "PermissionError") instead of [`KeyError`](../library/exceptions.xhtml#KeyError "KeyError") if the user doesn't have privileges. - The [`socket.socket.close()`](../library/socket.xhtml#socket.socket.close "socket.socket.close") method now raises an exception if an error (e.g. `EBADF`) was reported by the underlying system call. (Contributed by Martin Panter in [bpo-26685](https://bugs.python.org/issue26685) \[https://bugs.python.org/issue26685\].) - The *decode\_data* argument for the [`smtpd.SMTPChannel`](../library/smtpd.xhtml#smtpd.SMTPChannel "smtpd.SMTPChannel") and [`smtpd.SMTPServer`](../library/smtpd.xhtml#smtpd.SMTPServer "smtpd.SMTPServer") constructors is now `False` by default. This means that the argument passed to [`process_message()`](../library/smtpd.xhtml#smtpd.SMTPServer.process_message "smtpd.SMTPServer.process_message") is now a bytes object by default, and `process_message()` will be passed keyword arguments. Code that has already been updated in accordance with the deprecation warning generated by 3.5 will not be affected. - All optional arguments of the [`dump()`](../library/json.xhtml#json.dump "json.dump"), [`dumps()`](../library/json.xhtml#json.dumps "json.dumps"), [`load()`](../library/json.xhtml#json.load "json.load") and [`loads()`](../library/json.xhtml#json.loads "json.loads") functions and [`JSONEncoder`](../library/json.xhtml#json.JSONEncoder "json.JSONEncoder") and [`JSONDecoder`](../library/json.xhtml#json.JSONDecoder "json.JSONDecoder") class constructors in the [`json`](../library/json.xhtml#module-json "json: Encode and decode the JSON format.") module are now [keyword-only](../glossary.xhtml#keyword-only-parameter). (Contributed by Serhiy Storchaka in [bpo-18726](https://bugs.python.org/issue18726) \[https://bugs.python.org/issue18726\].) - [`type`](../library/functions.xhtml#type "type") 的子类如果未重载 `type.__new__`，将不再能使用一个参数的形式来获取对象的类型。 - As part of [**PEP 487**](https://www.python.org/dev/peps/pep-0487) \[https://www.python.org/dev/peps/pep-0487\], the handling of keyword arguments passed to [`type`](../library/functions.xhtml#type "type") (other than the metaclass hint, `metaclass`) is now consistently delegated to [`object.__init_subclass__()`](../reference/datamodel.xhtml#object.__init_subclass__ "object.__init_subclass__"). This means that `type.__new__()` and `type.__init__()` both now accept arbitrary keyword arguments, but [`object.__init_subclass__()`](../reference/datamodel.xhtml#object.__init_subclass__ "object.__init_subclass__") (which is called from `type.__new__()`) will reject them by default. Custom metaclasses accepting additional keyword arguments will need to adjust their calls to `type.__new__()` (whether direct or via [`super`](../library/functions.xhtml#super "super")) accordingly. - In `distutils.command.sdist.sdist`, the `default_format`attribute has been removed and is no longer honored. Instead, the gzipped tarfile format is the default on all platforms and no platform-specific selection is made. In environments where distributions are built on Windows and zip distributions are required, configure the project with a `setup.cfg` file containing the following: ``` [sdist] formats=zip ``` This behavior has also been backported to earlier Python versions by Setuptools 26.0.0. - In the [`urllib.request`](../library/urllib.request.xhtml#module-urllib.request "urllib.request: Extensible library for opening URLs.") module and the [`http.client.HTTPConnection.request()`](../library/http.client.xhtml#http.client.HTTPConnection.request "http.client.HTTPConnection.request") method, if no Content-Length header field has been specified and the request body is a file object, it is now sent with HTTP 1.1 chunked encoding. If a file object has to be sent to a HTTP 1.0 server, the Content-Length value now has to be specified by the caller. (Contributed by Demian Brecht and Rolf Krahl with tweaks from Martin Panter in [bpo-12319](https://bugs.python.org/issue12319) \[https://bugs.python.org/issue12319\].) - The [`DictReader`](../library/csv.xhtml#csv.DictReader "csv.DictReader") now returns rows of type [`OrderedDict`](../library/collections.xhtml#collections.OrderedDict "collections.OrderedDict"). (Contributed by Steve Holden in [bpo-27842](https://bugs.python.org/issue27842) \[https://bugs.python.org/issue27842\].) - The [`crypt.METHOD_CRYPT`](../library/crypt.xhtml#crypt.METHOD_CRYPT "crypt.METHOD_CRYPT") will no longer be added to `crypt.methods`if unsupported by the platform. (Contributed by Victor Stinner in [bpo-25287](https://bugs.python.org/issue25287) \[https://bugs.python.org/issue25287\].) - The *verbose* and *rename* arguments for [`namedtuple()`](../library/collections.xhtml#collections.namedtuple "collections.namedtuple") are now keyword-only. (Contributed by Raymond Hettinger in [bpo-25628](https://bugs.python.org/issue25628) \[https://bugs.python.org/issue25628\].) - On Linux, [`ctypes.util.find_library()`](../library/ctypes.xhtml#ctypes.util.find_library "ctypes.util.find_library") now looks in `LD_LIBRARY_PATH` for shared libraries. (Contributed by Vinay Sajip in [bpo-9998](https://bugs.python.org/issue9998) \[https://bugs.python.org/issue9998\].) - The [`imaplib.IMAP4`](../library/imaplib.xhtml#imaplib.IMAP4 "imaplib.IMAP4") class now handles flags containing the `']'` character in messages sent from the server to improve real-world compatibility. (Contributed by Lita Cho in [bpo-21815](https://bugs.python.org/issue21815) \[https://bugs.python.org/issue21815\].) - The `mmap.write()` function now returns the number of bytes written like other write methods. (Contributed by Jakub Stasiak in [bpo-26335](https://bugs.python.org/issue26335) \[https://bugs.python.org/issue26335\].) - The [`pkgutil.iter_modules()`](../library/pkgutil.xhtml#pkgutil.iter_modules "pkgutil.iter_modules") and [`pkgutil.walk_packages()`](../library/pkgutil.xhtml#pkgutil.walk_packages "pkgutil.walk_packages")functions now return [`ModuleInfo`](../library/pkgutil.xhtml#pkgutil.ModuleInfo "pkgutil.ModuleInfo") named tuples. (Contributed by Ramchandra Apte in [bpo-17211](https://bugs.python.org/issue17211) \[https://bugs.python.org/issue17211\].) - [`re.sub()`](../library/re.xhtml#re.sub "re.sub") now raises an error for invalid numerical group references in replacement templates even if the pattern is not found in the string. The error message for invalid group references now includes the group index and the position of the reference. (Contributed by SilentGhost, Serhiy Storchaka in [bpo-25953](https://bugs.python.org/issue25953) \[https://bugs.python.org/issue25953\].) - [`zipfile.ZipFile`](../library/zipfile.xhtml#zipfile.ZipFile "zipfile.ZipFile") will now raise [`NotImplementedError`](../library/exceptions.xhtml#NotImplementedError "NotImplementedError") for unrecognized compression values. Previously a plain [`RuntimeError`](../library/exceptions.xhtml#RuntimeError "RuntimeError")was raised. Additionally, calling [`ZipFile`](../library/zipfile.xhtml#zipfile.ZipFile "zipfile.ZipFile") methods on a closed ZipFile or calling the [`write()`](../library/zipfile.xhtml#zipfile.ZipFile.write "zipfile.ZipFile.write") method on a ZipFile created with mode `'r'` will raise a [`ValueError`](../library/exceptions.xhtml#ValueError "ValueError"). Previously, a [`RuntimeError`](../library/exceptions.xhtml#RuntimeError "RuntimeError") was raised in those scenarios. - when custom metaclasses are combined with zero-argument [`super()`](../library/functions.xhtml#super "super") or direct references from methods to the implicit `__class__` closure variable, the implicit `__classcell__` namespace entry must now be passed up to `type.__new__` for initialisation. Failing to do so will result in a [`DeprecationWarning`](../library/exceptions.xhtml#DeprecationWarning "DeprecationWarning") in Python 3.6 and a [`RuntimeError`](../library/exceptions.xhtml#RuntimeError "RuntimeError") in Python 3.8. - With the introduction of [`ModuleNotFoundError`](../library/exceptions.xhtml#ModuleNotFoundError "ModuleNotFoundError"), import system consumers may start expecting import system replacements to raise that more specific exception when appropriate, rather than the less-specific [`ImportError`](../library/exceptions.xhtml#ImportError "ImportError"). To provide future compatibility with such consumers, implementors of alternative import systems that completely replace [`__import__()`](../library/functions.xhtml#__import__ "__import__") will need to update their implementations to raise the new subclass when a module can't be found at all. Implementors of compliant plugins to the default import system shouldn't need to make any changes, as the default import system will raise the new subclass when appropriate. ### C API 中的改变 - The [`PyMem_Malloc()`](../c-api/memory.xhtml#c.PyMem_Malloc "PyMem_Malloc") allocator family now uses the [pymalloc allocator](../c-api/memory.xhtml#pymalloc) rather than the system `malloc()`. Applications calling [`PyMem_Malloc()`](../c-api/memory.xhtml#c.PyMem_Malloc "PyMem_Malloc") without holding the GIL can now crash. Set the [`PYTHONMALLOC`](../using/cmdline.xhtml#envvar-PYTHONMALLOC) environment variable to `debug` to validate the usage of memory allocators in your application. See [bpo-26249](https://bugs.python.org/issue26249) \[https://bugs.python.org/issue26249\]. - [`Py_Exit()`](../c-api/sys.xhtml#c.Py_Exit "Py_Exit") (and the main interpreter) now override the exit status with 120 if flushing buffered data failed. See [bpo-5319](https://bugs.python.org/issue5319) \[https://bugs.python.org/issue5319\]. ### CPython 字节码的改变 There have been several major changes to the [bytecode](../glossary.xhtml#term-bytecode) in Python 3.6. - The Python interpreter now uses a 16-bit wordcode instead of bytecode. (Contributed by Demur Rumed with input and reviews from Serhiy Storchaka and Victor Stinner in [bpo-26647](https://bugs.python.org/issue26647) \[https://bugs.python.org/issue26647\] and [bpo-28050](https://bugs.python.org/issue28050) \[https://bugs.python.org/issue28050\].) - The new [`FORMAT_VALUE`](../library/dis.xhtml#opcode-FORMAT_VALUE) and [`BUILD_STRING`](../library/dis.xhtml#opcode-BUILD_STRING) opcodes as part of the [formatted string literal](#whatsnew36-pep498) implementation. (Contributed by Eric Smith in [bpo-25483](https://bugs.python.org/issue25483) \[https://bugs.python.org/issue25483\] and Serhiy Storchaka in [bpo-27078](https://bugs.python.org/issue27078) \[https://bugs.python.org/issue27078\].) - The new [`BUILD_CONST_KEY_MAP`](../library/dis.xhtml#opcode-BUILD_CONST_KEY_MAP) opcode to optimize the creation of dictionaries with constant keys. (Contributed by Serhiy Storchaka in [bpo-27140](https://bugs.python.org/issue27140) \[https://bugs.python.org/issue27140\].) - The function call opcodes have been heavily reworked for better performance and simpler implementation. The [`MAKE_FUNCTION`](../library/dis.xhtml#opcode-MAKE_FUNCTION), [`CALL_FUNCTION`](../library/dis.xhtml#opcode-CALL_FUNCTION), [`CALL_FUNCTION_KW`](../library/dis.xhtml#opcode-CALL_FUNCTION_KW) and [`BUILD_MAP_UNPACK_WITH_CALL`](../library/dis.xhtml#opcode-BUILD_MAP_UNPACK_WITH_CALL) opcodes have been modified, the new [`CALL_FUNCTION_EX`](../library/dis.xhtml#opcode-CALL_FUNCTION_EX) and [`BUILD_TUPLE_UNPACK_WITH_CALL`](../library/dis.xhtml#opcode-BUILD_TUPLE_UNPACK_WITH_CALL) have been added, and `CALL_FUNCTION_VAR`, `CALL_FUNCTION_VAR_KW` and `MAKE_CLOSURE` opcodes have been removed. (Contributed by Demur Rumed in [bpo-27095](https://bugs.python.org/issue27095) \[https://bugs.python.org/issue27095\], and Serhiy Storchaka in [bpo-27213](https://bugs.python.org/issue27213) \[https://bugs.python.org/issue27213\], [bpo-28257](https://bugs.python.org/issue28257) \[https://bugs.python.org/issue28257\].) - The new [`SETUP_ANNOTATIONS`](../library/dis.xhtml#opcode-SETUP_ANNOTATIONS) and `STORE_ANNOTATION` opcodes have been added to support the new [variable annotation](../glossary.xhtml#term-variable-annotation) syntax. (Contributed by Ivan Levkivskyi in [bpo-27985](https://bugs.python.org/issue27985) \[https://bugs.python.org/issue27985\].) ## Python 3.6.2 中的重要变化 ### New `make regen-all` build target To simplify cross-compilation, and to ensure that CPython can reliably be compiled without requiring an existing version of Python to already be available, the autotools-based build system no longer attempts to implicitly recompile generated files based on file modification times. Instead, a new `make regen-all` command has been added to force regeneration of these files when desired (e.g. after an initial version of Python has already been built based on the pregenerated versions). More selective regeneration targets are also defined - see [Makefile.pre.in](https://github.com/python/cpython/tree/3.7/Makefile.pre.in) \[https://github.com/python/cpython/tree/3.7/Makefile.pre.in\] for details. (Contributed by Victor Stinner in [bpo-23404](https://bugs.python.org/issue23404) \[https://bugs.python.org/issue23404\].) 3\.6.2 新版功能. ### Removal of `make touch` build target The `make touch` build target previously used to request implicit regeneration of generated files by updating their modification times has been removed. It has been replaced by the new `make regen-all` target. (Contributed by Victor Stinner in [bpo-23404](https://bugs.python.org/issue23404) \[https://bugs.python.org/issue23404\].) 在 3.6.2 版更改. ## Python 3.6.4 中的重要变化 The `PyExc_RecursionErrorInst` singleton that was part of the public API has been removed as its members being never cleared may cause a segfault during finalization of the interpreter. (Contributed by Xavier de Gaye in [bpo-22898](https://bugs.python.org/issue22898) \[https://bugs.python.org/issue22898\] and [bpo-30697](https://bugs.python.org/issue30697) \[https://bugs.python.org/issue30697\].) ## Python 3.6.5 中的重要变化 The [`locale.localeconv()`](../library/locale.xhtml#locale.localeconv "locale.localeconv") function now sets temporarily the `LC_CTYPE`locale to the `LC_NUMERIC` locale in some cases. (Contributed by Victor Stinner in [bpo-31900](https://bugs.python.org/issue31900) \[https://bugs.python.org/issue31900\].) ## Python 3.6.7 中的重要变化 In 3.6.7 the [`tokenize`](../library/tokenize.xhtml#module-tokenize "tokenize: Lexical scanner for Python source code.") module now implicitly emits a `NEWLINE` token when provided with input that does not have a trailing new line. This behavior now matches what the C tokenizer does internally. (Contributed by Ammar Askar in [bpo-33899](https://bugs.python.org/issue33899) \[https://bugs.python.org/issue33899\].) ### 导航 - [索引](../genindex.xhtml "总目录") - [模块](../py-modindex.xhtml "Python 模块索引") | - [下一页](3.5.xhtml "Python 3.5 有什么新变化") | - [上一页](3.7.xhtml "Python 3.7 有什么新变化") | -  - [Python](https://www.python.org/) » - zh\_CN 3.7.3 [文档](../index.xhtml) » - [Python 有什么新变化？](index.xhtml) » - $('.inline-search').show(0); | © [版权所有](../copyright.xhtml) 2001-2019, Python Software Foundation. Python 软件基金会是一个非盈利组织。 [请捐助。](https://www.python.org/psf/donations/) 最后更新于 5月 21, 2019. [发现了问题](../bugs.xhtml)？ 使用[Sphinx](http://sphinx.pocoo.org/)1.8.4 创建。