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# [`enum`](#module-enum "enum: Implementation of an enumeration class.") --- Support for enumerations
3\.4 新版功能.
**Source code:** [Lib/enum.py](https://github.com/python/cpython/tree/3.7/Lib/enum.py) \[https://github.com/python/cpython/tree/3.7/Lib/enum.py\]
- - - - - -
An enumeration is a set of symbolic names (members) bound to unique, constant values. Within an enumeration, the members can be compared by identity, and the enumeration itself can be iterated over.
## 模块内容
This module defines four enumeration classes that can be used to define unique sets of names and values: [`Enum`](#enum.Enum "enum.Enum"), [`IntEnum`](#enum.IntEnum "enum.IntEnum"), [`Flag`](#enum.Flag "enum.Flag"), and [`IntFlag`](#enum.IntFlag "enum.IntFlag"). It also defines one decorator, [`unique()`](#enum.unique "enum.unique"), and one helper, [`auto`](#enum.auto "enum.auto").
*class* `enum.``Enum`Base class for creating enumerated constants. See section [Functional API](#functional-api) for an alternate construction syntax.
*class* `enum.``IntEnum`Base class for creating enumerated constants that are also subclasses of [`int`](functions.xhtml#int "int").
*class* `enum.``IntFlag`Base class for creating enumerated constants that can be combined using the bitwise operators without losing their [`IntFlag`](#enum.IntFlag "enum.IntFlag") membership. [`IntFlag`](#enum.IntFlag "enum.IntFlag") members are also subclasses of [`int`](functions.xhtml#int "int").
*class* `enum.``Flag`Base class for creating enumerated constants that can be combined using the bitwise operations without losing their [`Flag`](#enum.Flag "enum.Flag") membership.
`enum.``unique`()Enum class decorator that ensures only one name is bound to any one value.
*class* `enum.``auto`Instances are replaced with an appropriate value for Enum members.
3\.6 新版功能: `Flag`, `IntFlag`, `auto`
## Creating an Enum
Enumerations are created using the [`class`](../reference/compound_stmts.xhtml#class) syntax, which makes them easy to read and write. An alternative creation method is described in [Functional API](#functional-api). To define an enumeration, subclass [`Enum`](#enum.Enum "enum.Enum") as follows:
```
>>> from enum import Enum
>>> class Color(Enum):
... RED = 1
... GREEN = 2
... BLUE = 3
...
```
注解
Enum member values
Member values can be anything: [`int`](functions.xhtml#int "int"), [`str`](stdtypes.xhtml#str "str"), etc.. If the exact value is unimportant you may use [`auto`](#enum.auto "enum.auto") instances and an appropriate value will be chosen for you. Care must be taken if you mix [`auto`](#enum.auto "enum.auto") with other values.
注解
Nomenclature
- The class `Color` is an *enumeration* (or *enum*)
- The attributes `Color.RED`, `Color.GREEN`, etc., are *enumeration members* (or *enum members*) and are functionally constants.
- The enum members have *names* and *values* (the name of `Color.RED` is `RED`, the value of `Color.BLUE` is `3`, etc.)
注解
Even though we use the [`class`](../reference/compound_stmts.xhtml#class) syntax to create Enums, Enums are not normal Python classes. See [How are Enums different?](#how-are-enums-different) for more details.
Enumeration members have human readable string representations:
```
>>> print(Color.RED)
Color.RED
```
...while their `repr` has more information:
```
>>> print(repr(Color.RED))
<Color.RED: 1>
```
The *type* of an enumeration member is the enumeration it belongs to:
```
>>> type(Color.RED)
<enum 'Color'>
>>> isinstance(Color.GREEN, Color)
True
>>>
```
Enum members also have a property that contains just their item name:
```
>>> print(Color.RED.name)
RED
```
Enumerations support iteration, in definition order:
```
>>> class Shake(Enum):
... VANILLA = 7
... CHOCOLATE = 4
... COOKIES = 9
... MINT = 3
...
>>> for shake in Shake:
... print(shake)
...
Shake.VANILLA
Shake.CHOCOLATE
Shake.COOKIES
Shake.MINT
```
Enumeration members are hashable, so they can be used in dictionaries and sets:
```
>>> apples = {}
>>> apples[Color.RED] = 'red delicious'
>>> apples[Color.GREEN] = 'granny smith'
>>> apples == {Color.RED: 'red delicious', Color.GREEN: 'granny smith'}
True
```
## Programmatic access to enumeration members and their attributes
Sometimes it's useful to access members in enumerations programmatically (i.e. situations where `Color.RED` won't do because the exact color is not known at program-writing time). `Enum` allows such access:
```
>>> Color(1)
<Color.RED: 1>
>>> Color(3)
<Color.BLUE: 3>
```
If you want to access enum members by *name*, use item access:
```
>>> Color['RED']
<Color.RED: 1>
>>> Color['GREEN']
<Color.GREEN: 2>
```
If you have an enum member and need its `name` or `value`:
```
>>> member = Color.RED
>>> member.name
'RED'
>>> member.value
1
```
## Duplicating enum members and values
Having two enum members with the same name is invalid:
```
>>> class Shape(Enum):
... SQUARE = 2
... SQUARE = 3
...
Traceback (most recent call last):
...
TypeError: Attempted to reuse key: 'SQUARE'
```
However, two enum members are allowed to have the same value. Given two members A and B with the same value (and A defined first), B is an alias to A. By-value lookup of the value of A and B will return A. By-name lookup of B will also return A:
```
>>> class Shape(Enum):
... SQUARE = 2
... DIAMOND = 1
... CIRCLE = 3
... ALIAS_FOR_SQUARE = 2
...
>>> Shape.SQUARE
<Shape.SQUARE: 2>
>>> Shape.ALIAS_FOR_SQUARE
<Shape.SQUARE: 2>
>>> Shape(2)
<Shape.SQUARE: 2>
```
注解
Attempting to create a member with the same name as an already defined attribute (another member, a method, etc.) or attempting to create an attribute with the same name as a member is not allowed.
## Ensuring unique enumeration values
By default, enumerations allow multiple names as aliases for the same value. When this behavior isn't desired, the following decorator can be used to ensure each value is used only once in the enumeration:
`@``enum.``unique`A [`class`](../reference/compound_stmts.xhtml#class) decorator specifically for enumerations. It searches an enumeration's `__members__` gathering any aliases it finds; if any are found [`ValueError`](exceptions.xhtml#ValueError "ValueError") is raised with the details:
```
>>> from enum import Enum, unique
>>> @unique
... class Mistake(Enum):
... ONE = 1
... TWO = 2
... THREE = 3
... FOUR = 3
...
Traceback (most recent call last):
...
ValueError: duplicate values found in <enum 'Mistake'>: FOUR -> THREE
```
## Using automatic values
If the exact value is unimportant you can use [`auto`](#enum.auto "enum.auto"):
```
>>> 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>]
```
The values are chosen by `_generate_next_value_()`, which can be overridden:
```
>>> class AutoName(Enum):
... def _generate_next_value_(name, start, count, last_values):
... return name
...
>>> class Ordinal(AutoName):
... NORTH = auto()
... SOUTH = auto()
... EAST = auto()
... WEST = auto()
...
>>> list(Ordinal)
[<Ordinal.NORTH: 'NORTH'>, <Ordinal.SOUTH: 'SOUTH'>, <Ordinal.EAST: 'EAST'>, <Ordinal.WEST: 'WEST'>]
```
注解
The goal of the default `_generate_next_value_()` methods is to provide the next [`int`](functions.xhtml#int "int") in sequence with the last [`int`](functions.xhtml#int "int") provided, but the way it does this is an implementation detail and may change.
## Iteration
Iterating over the members of an enum does not provide the aliases:
```
>>> list(Shape)
[<Shape.SQUARE: 2>, <Shape.DIAMOND: 1>, <Shape.CIRCLE: 3>]
```
The special attribute `__members__` is an ordered dictionary mapping names to members. It includes all names defined in the enumeration, including the aliases:
```
>>> for name, member in Shape.__members__.items():
... name, member
...
('SQUARE', <Shape.SQUARE: 2>)
('DIAMOND', <Shape.DIAMOND: 1>)
('CIRCLE', <Shape.CIRCLE: 3>)
('ALIAS_FOR_SQUARE', <Shape.SQUARE: 2>)
```
The `__members__` attribute can be used for detailed programmatic access to the enumeration members. For example, finding all the aliases:
```
>>> [name for name, member in Shape.__members__.items() if member.name != name]
['ALIAS_FOR_SQUARE']
```
## 比较
Enumeration members are compared by identity:
```
>>> Color.RED is Color.RED
True
>>> Color.RED is Color.BLUE
False
>>> Color.RED is not Color.BLUE
True
```
Ordered comparisons between enumeration values are *not* supported. Enum members are not integers (but see [IntEnum](#intenum) below):
```
>>> Color.RED < Color.BLUE
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
TypeError: '<' not supported between instances of 'Color' and 'Color'
```
Equality comparisons are defined though:
```
>>> Color.BLUE == Color.RED
False
>>> Color.BLUE != Color.RED
True
>>> Color.BLUE == Color.BLUE
True
```
Comparisons against non-enumeration values will always compare not equal (again, [`IntEnum`](#enum.IntEnum "enum.IntEnum") was explicitly designed to behave differently, see below):
```
>>> Color.BLUE == 2
False
```
## Allowed members and attributes of enumerations
The examples above use integers for enumeration values. Using integers is short and handy (and provided by default by the [Functional API](#functional-api)), but not strictly enforced. In the vast majority of use-cases, one doesn't care what the actual value of an enumeration is. But if the value *is* important, enumerations can have arbitrary values.
Enumerations are Python classes, and can have methods and special methods as usual. If we have this enumeration:
```
>>> class Mood(Enum):
... FUNKY = 1
... HAPPY = 3
...
... def describe(self):
... # self is the member here
... return self.name, self.value
...
... def __str__(self):
... return 'my custom str! {0}'.format(self.value)
...
... @classmethod
... def favorite_mood(cls):
... # cls here is the enumeration
... return cls.HAPPY
...
```
Then:
```
>>> Mood.favorite_mood()
<Mood.HAPPY: 3>
>>> Mood.HAPPY.describe()
('HAPPY', 3)
>>> str(Mood.FUNKY)
'my custom str! 1'
```
The rules for what is allowed are as follows: names that start and end with a single underscore are reserved by enum and cannot be used; all other attributes defined within an enumeration will become members of this enumeration, with the exception of special methods ([`__str__()`](../reference/datamodel.xhtml#object.__str__ "object.__str__"), [`__add__()`](../reference/datamodel.xhtml#object.__add__ "object.__add__"), etc.), descriptors (methods are also descriptors), and variable names listed in `_ignore_`.
Note: if your enumeration defines [`__new__()`](../reference/datamodel.xhtml#object.__new__ "object.__new__") and/or [`__init__()`](../reference/datamodel.xhtml#object.__init__ "object.__init__") then whatever value(s) were given to the enum member will be passed into those methods. See [Planet](#planet) for an example.
## Restricted Enum subclassing
A new [`Enum`](#enum.Enum "enum.Enum") class must have one base Enum class, up to one concrete data type, and as many [`object`](functions.xhtml#object "object")-based mixin classes as needed. The order of these base classes is:
```
class EnumName([mix-in, ...,] [data-type,] base-enum):
pass
```
Also, subclassing an enumeration is allowed only if the enumeration does not define any members. So this is forbidden:
```
>>> class MoreColor(Color):
... PINK = 17
...
Traceback (most recent call last):
...
TypeError: Cannot extend enumerations
```
But this is allowed:
```
>>> class Foo(Enum):
... def some_behavior(self):
... pass
...
>>> class Bar(Foo):
... HAPPY = 1
... SAD = 2
...
```
Allowing subclassing of enums that define members would lead to a violation of some important invariants of types and instances. On the other hand, it makes sense to allow sharing some common behavior between a group of enumerations. (See [OrderedEnum](#orderedenum) for an example.)
## Pickling
Enumerations can be pickled and unpickled:
```
>>> from test.test_enum import Fruit
>>> from pickle import dumps, loads
>>> Fruit.TOMATO is loads(dumps(Fruit.TOMATO))
True
```
The usual restrictions for pickling apply: picklable enums must be defined in the top level of a module, since unpickling requires them to be importable from that module.
注解
With pickle protocol version 4 it is possible to easily pickle enums nested in other classes.
It is possible to modify how Enum members are pickled/unpickled by defining [`__reduce_ex__()`](pickle.xhtml#object.__reduce_ex__ "object.__reduce_ex__") in the enumeration class.
## Functional API
The [`Enum`](#enum.Enum "enum.Enum") class is callable, providing the following functional API:
```
>>> Animal = Enum('Animal', 'ANT BEE CAT DOG')
>>> Animal
<enum 'Animal'>
>>> Animal.ANT
<Animal.ANT: 1>
>>> Animal.ANT.value
1
>>> list(Animal)
[<Animal.ANT: 1>, <Animal.BEE: 2>, <Animal.CAT: 3>, <Animal.DOG: 4>]
```
The semantics of this API resemble [`namedtuple`](collections.xhtml#collections.namedtuple "collections.namedtuple"). The first argument of the call to [`Enum`](#enum.Enum "enum.Enum") is the name of the enumeration.
The second argument is the *source* of enumeration member names. It can be a whitespace-separated string of names, a sequence of names, a sequence of 2-tuples with key/value pairs, or a mapping (e.g. dictionary) of names to values. The last two options enable assigning arbitrary values to enumerations; the others auto-assign increasing integers starting with 1 (use the `start` parameter to specify a different starting value). A new class derived from [`Enum`](#enum.Enum "enum.Enum") is returned. In other words, the above assignment to `Animal` is equivalent to:
```
>>> class Animal(Enum):
... ANT = 1
... BEE = 2
... CAT = 3
... DOG = 4
...
```
The reason for defaulting to `1` as the starting number and not `0` is that `0` is `False` in a boolean sense, but enum members all evaluate to `True`.
Pickling enums created with the functional API can be tricky as frame stack implementation details are used to try and figure out which module the enumeration is being created in (e.g. it will fail if you use a utility function in separate module, and also may not work on IronPython or Jython). The solution is to specify the module name explicitly as follows:
```
>>> Animal = Enum('Animal', 'ANT BEE CAT DOG', module=__name__)
```
警告
If `module` is not supplied, and Enum cannot determine what it is, the new Enum members will not be unpicklable; to keep errors closer to the source, pickling will be disabled.
The new pickle protocol 4 also, in some circumstances, relies on [`__qualname__`](stdtypes.xhtml#definition.__qualname__ "definition.__qualname__") being set to the location where pickle will be able to find the class. For example, if the class was made available in class SomeData in the global scope:
```
>>> Animal = Enum('Animal', 'ANT BEE CAT DOG', qualname='SomeData.Animal')
```
The complete signature is:
```
Enum(value='NewEnumName', names=<...>, *, module='...', qualname='...', type=<mixed-in class>, start=1)
```
值What the new Enum class will record as its name.
namesThe Enum members. This can be a whitespace or comma separated string (values will start at 1 unless otherwise specified):
```
'RED GREEN BLUE' | 'RED,GREEN,BLUE' | 'RED, GREEN, BLUE'
```
or an iterator of names:
```
['RED', 'GREEN', 'BLUE']
```
or an iterator of (name, value) pairs:
```
[('CYAN', 4), ('MAGENTA', 5), ('YELLOW', 6)]
```
or a mapping:
```
{'CHARTREUSE': 7, 'SEA_GREEN': 11, 'ROSEMARY': 42}
```
模块name of module where new Enum class can be found.
qualnamewhere in module new Enum class can be found.
类型type to mix in to new Enum class.
startnumber to start counting at if only names are passed in.
在 3.5 版更改: The *start* parameter was added.
## Derived Enumerations
### IntEnum
The first variation of [`Enum`](#enum.Enum "enum.Enum") that is provided is also a subclass of [`int`](functions.xhtml#int "int"). Members of an [`IntEnum`](#enum.IntEnum "enum.IntEnum") can be compared to integers; by extension, integer enumerations of different types can also be compared to each other:
```
>>> from enum import IntEnum
>>> class Shape(IntEnum):
... CIRCLE = 1
... SQUARE = 2
...
>>> class Request(IntEnum):
... POST = 1
... GET = 2
...
>>> Shape == 1
False
>>> Shape.CIRCLE == 1
True
>>> Shape.CIRCLE == Request.POST
True
```
However, they still can't be compared to standard [`Enum`](#enum.Enum "enum.Enum") enumerations:
```
>>> class Shape(IntEnum):
... CIRCLE = 1
... SQUARE = 2
...
>>> class Color(Enum):
... RED = 1
... GREEN = 2
...
>>> Shape.CIRCLE == Color.RED
False
```
[`IntEnum`](#enum.IntEnum "enum.IntEnum") values behave like integers in other ways you'd expect:
```
>>> int(Shape.CIRCLE)
1
>>> ['a', 'b', 'c'][Shape.CIRCLE]
'b'
>>> [i for i in range(Shape.SQUARE)]
[0, 1]
```
### IntFlag
The next variation of [`Enum`](#enum.Enum "enum.Enum") provided, [`IntFlag`](#enum.IntFlag "enum.IntFlag"), is also based on [`int`](functions.xhtml#int "int"). The difference being [`IntFlag`](#enum.IntFlag "enum.IntFlag") members can be combined using the bitwise operators (&, |, ^, ~) and the result is still an [`IntFlag`](#enum.IntFlag "enum.IntFlag") member. However, as the name implies, [`IntFlag`](#enum.IntFlag "enum.IntFlag")members also subclass [`int`](functions.xhtml#int "int") and can be used wherever an [`int`](functions.xhtml#int "int") is used. Any operation on an [`IntFlag`](#enum.IntFlag "enum.IntFlag") member besides the bit-wise operations will lose the [`IntFlag`](#enum.IntFlag "enum.IntFlag") membership.
3\.6 新版功能.
Sample [`IntFlag`](#enum.IntFlag "enum.IntFlag") class:
```
>>> from enum import IntFlag
>>> class Perm(IntFlag):
... R = 4
... W = 2
... X = 1
...
>>> Perm.R | Perm.W
<Perm.R|W: 6>
>>> Perm.R + Perm.W
6
>>> RW = Perm.R | Perm.W
>>> Perm.R in RW
True
```
It is also possible to name the combinations:
```
>>> class Perm(IntFlag):
... R = 4
... W = 2
... X = 1
... RWX = 7
>>> Perm.RWX
<Perm.RWX: 7>
>>> ~Perm.RWX
<Perm.-8: -8>
```
Another important difference between [`IntFlag`](#enum.IntFlag "enum.IntFlag") and [`Enum`](#enum.Enum "enum.Enum") is that if no flags are set (the value is 0), its boolean evaluation is [`False`](constants.xhtml#False "False"):
```
>>> Perm.R & Perm.X
<Perm.0: 0>
>>> bool(Perm.R & Perm.X)
False
```
Because [`IntFlag`](#enum.IntFlag "enum.IntFlag") members are also subclasses of [`int`](functions.xhtml#int "int") they can be combined with them:
```
>>> Perm.X | 8
<Perm.8|X: 9>
```
### 标志
The last variation is [`Flag`](#enum.Flag "enum.Flag"). Like [`IntFlag`](#enum.IntFlag "enum.IntFlag"), [`Flag`](#enum.Flag "enum.Flag")members can be combined using the bitwise operators (&, |, ^, ~). Unlike [`IntFlag`](#enum.IntFlag "enum.IntFlag"), they cannot be combined with, nor compared against, any other [`Flag`](#enum.Flag "enum.Flag") enumeration, nor [`int`](functions.xhtml#int "int"). While it is possible to specify the values directly it is recommended to use [`auto`](#enum.auto "enum.auto") as the value and let [`Flag`](#enum.Flag "enum.Flag") select an appropriate value.
3\.6 新版功能.
Like [`IntFlag`](#enum.IntFlag "enum.IntFlag"), if a combination of [`Flag`](#enum.Flag "enum.Flag") members results in no flags being set, the boolean evaluation is [`False`](constants.xhtml#False "False"):
```
>>> from enum import Flag, auto
>>> class Color(Flag):
... RED = auto()
... BLUE = auto()
... GREEN = auto()
...
>>> Color.RED & Color.GREEN
<Color.0: 0>
>>> bool(Color.RED & Color.GREEN)
False
```
Individual flags should have values that are powers of two (1, 2, 4, 8, ...), while combinations of flags won't:
```
>>> class Color(Flag):
... RED = auto()
... BLUE = auto()
... GREEN = auto()
... WHITE = RED | BLUE | GREEN
...
>>> Color.WHITE
<Color.WHITE: 7>
```
Giving a name to the "no flags set" condition does not change its boolean value:
```
>>> class Color(Flag):
... BLACK = 0
... RED = auto()
... BLUE = auto()
... GREEN = auto()
...
>>> Color.BLACK
<Color.BLACK: 0>
>>> bool(Color.BLACK)
False
```
注解
For the majority of new code, [`Enum`](#enum.Enum "enum.Enum") and [`Flag`](#enum.Flag "enum.Flag") are strongly recommended, since [`IntEnum`](#enum.IntEnum "enum.IntEnum") and [`IntFlag`](#enum.IntFlag "enum.IntFlag") break some semantic promises of an enumeration (by being comparable to integers, and thus by transitivity to other unrelated enumerations). [`IntEnum`](#enum.IntEnum "enum.IntEnum")and [`IntFlag`](#enum.IntFlag "enum.IntFlag") should be used only in cases where [`Enum`](#enum.Enum "enum.Enum") and [`Flag`](#enum.Flag "enum.Flag") will not do; for example, when integer constants are replaced with enumerations, or for interoperability with other systems.
### Others
While [`IntEnum`](#enum.IntEnum "enum.IntEnum") is part of the [`enum`](#module-enum "enum: Implementation of an enumeration class.") module, it would be very simple to implement independently:
```
class IntEnum(int, Enum):
pass
```
This demonstrates how similar derived enumerations can be defined; for example a `StrEnum` that mixes in [`str`](stdtypes.xhtml#str "str") instead of [`int`](functions.xhtml#int "int").
Some rules:
1. When subclassing [`Enum`](#enum.Enum "enum.Enum"), mix-in types must appear before [`Enum`](#enum.Enum "enum.Enum") itself in the sequence of bases, as in the [`IntEnum`](#enum.IntEnum "enum.IntEnum")example above.
2. While [`Enum`](#enum.Enum "enum.Enum") can have members of any type, once you mix in an additional type, all the members must have values of that type, e.g. [`int`](functions.xhtml#int "int") above. This restriction does not apply to mix-ins which only add methods and don't specify another data type such as [`int`](functions.xhtml#int "int") or [`str`](stdtypes.xhtml#str "str").
3. When another data type is mixed in, the `value` attribute is *not the same* as the enum member itself, although it is equivalent and will compare equal.
4. %-style formatting: %s and %r call the [`Enum`](#enum.Enum "enum.Enum") class's [`__str__()`](../reference/datamodel.xhtml#object.__str__ "object.__str__") and [`__repr__()`](../reference/datamodel.xhtml#object.__repr__ "object.__repr__") respectively; other codes (such as %i or %h for IntEnum) treat the enum member as its mixed-in type.
5. [Formatted string literals](../reference/lexical_analysis.xhtml#f-strings), [`str.format()`](stdtypes.xhtml#str.format "str.format"), and [`format()`](functions.xhtml#format "format") will use the mixed-in type's [`__format__()`](../reference/datamodel.xhtml#object.__format__ "object.__format__"). If the [`Enum`](#enum.Enum "enum.Enum") class's [`str()`](stdtypes.xhtml#str "str") or [`repr()`](functions.xhtml#repr "repr") is desired, use the !s or !r format codes.
## Interesting examples
While [`Enum`](#enum.Enum "enum.Enum"), [`IntEnum`](#enum.IntEnum "enum.IntEnum"), [`IntFlag`](#enum.IntFlag "enum.IntFlag"), and [`Flag`](#enum.Flag "enum.Flag") are expected to cover the majority of use-cases, they cannot cover them all. Here are recipes for some different types of enumerations that can be used directly, or as examples for creating one's own.
### Omitting values
In many use-cases one doesn't care what the actual value of an enumeration is. There are several ways to define this type of simple enumeration:
- use instances of [`auto`](#enum.auto "enum.auto") for the value
- use instances of [`object`](functions.xhtml#object "object") as the value
- use a descriptive string as the value
- use a tuple as the value and a custom [`__new__()`](../reference/datamodel.xhtml#object.__new__ "object.__new__") to replace the tuple with an [`int`](functions.xhtml#int "int") value
Using any of these methods signifies to the user that these values are not important, and also enables one to add, remove, or reorder members without having to renumber the remaining members.
Whichever method you choose, you should provide a [`repr()`](functions.xhtml#repr "repr") that also hides the (unimportant) value:
```
>>> class NoValue(Enum):
... def __repr__(self):
... return '<%s.%s>' % (self.__class__.__name__, self.name)
...
```
#### Using [`auto`](#enum.auto "enum.auto")
Using [`auto`](#enum.auto "enum.auto") would look like:
```
>>> class Color(NoValue):
... RED = auto()
... BLUE = auto()
... GREEN = auto()
...
>>> Color.GREEN
<Color.GREEN>
```
#### Using [`object`](functions.xhtml#object "object")
Using [`object`](functions.xhtml#object "object") would look like:
```
>>> class Color(NoValue):
... RED = object()
... GREEN = object()
... BLUE = object()
...
>>> Color.GREEN
<Color.GREEN>
```
#### Using a descriptive string
Using a string as the value would look like:
```
>>> class Color(NoValue):
... RED = 'stop'
... GREEN = 'go'
... BLUE = 'too fast!'
...
>>> Color.GREEN
<Color.GREEN>
>>> Color.GREEN.value
'go'
```
#### Using a custom [`__new__()`](../reference/datamodel.xhtml#object.__new__ "object.__new__")
Using an auto-numbering [`__new__()`](../reference/datamodel.xhtml#object.__new__ "object.__new__") would look like:
```
>>> class AutoNumber(NoValue):
... def __new__(cls):
... value = len(cls.__members__) + 1
... obj = object.__new__(cls)
... obj._value_ = value
... return obj
...
>>> class Color(AutoNumber):
... RED = ()
... GREEN = ()
... BLUE = ()
...
>>> Color.GREEN
<Color.GREEN>
>>> Color.GREEN.value
2
```
注解
The [`__new__()`](../reference/datamodel.xhtml#object.__new__ "object.__new__") method, if defined, is used during creation of the Enum members; it is then replaced by Enum's [`__new__()`](../reference/datamodel.xhtml#object.__new__ "object.__new__") which is used after class creation for lookup of existing members.
### OrderedEnum
An ordered enumeration that is not based on [`IntEnum`](#enum.IntEnum "enum.IntEnum") and so maintains the normal [`Enum`](#enum.Enum "enum.Enum") invariants (such as not being comparable to other enumerations):
```
>>> class OrderedEnum(Enum):
... def __ge__(self, other):
... if self.__class__ is other.__class__:
... return self.value >= other.value
... return NotImplemented
... def __gt__(self, other):
... if self.__class__ is other.__class__:
... return self.value > other.value
... return NotImplemented
... def __le__(self, other):
... if self.__class__ is other.__class__:
... return self.value <= other.value
... return NotImplemented
... def __lt__(self, other):
... if self.__class__ is other.__class__:
... return self.value < other.value
... return NotImplemented
...
>>> class Grade(OrderedEnum):
... A = 5
... B = 4
... C = 3
... D = 2
... F = 1
...
>>> Grade.C < Grade.A
True
```
### DuplicateFreeEnum
Raises an error if a duplicate member name is found instead of creating an alias:
```
>>> class DuplicateFreeEnum(Enum):
... def __init__(self, *args):
... cls = self.__class__
... if any(self.value == e.value for e in cls):
... a = self.name
... e = cls(self.value).name
... raise ValueError(
... "aliases not allowed in DuplicateFreeEnum: %r --> %r"
... % (a, e))
...
>>> class Color(DuplicateFreeEnum):
... RED = 1
... GREEN = 2
... BLUE = 3
... GRENE = 2
...
Traceback (most recent call last):
...
ValueError: aliases not allowed in DuplicateFreeEnum: 'GRENE' --> 'GREEN'
```
注解
This is a useful example for subclassing Enum to add or change other behaviors as well as disallowing aliases. If the only desired change is disallowing aliases, the [`unique()`](#enum.unique "enum.unique") decorator can be used instead.
### Planet
If [`__new__()`](../reference/datamodel.xhtml#object.__new__ "object.__new__") or [`__init__()`](../reference/datamodel.xhtml#object.__init__ "object.__init__") is defined the value of the enum member will be passed to those methods:
```
>>> class Planet(Enum):
... MERCURY = (3.303e+23, 2.4397e6)
... VENUS = (4.869e+24, 6.0518e6)
... EARTH = (5.976e+24, 6.37814e6)
... MARS = (6.421e+23, 3.3972e6)
... JUPITER = (1.9e+27, 7.1492e7)
... SATURN = (5.688e+26, 6.0268e7)
... URANUS = (8.686e+25, 2.5559e7)
... NEPTUNE = (1.024e+26, 2.4746e7)
... def __init__(self, mass, radius):
... self.mass = mass # in kilograms
... self.radius = radius # in meters
... @property
... def surface_gravity(self):
... # universal gravitational constant (m3 kg-1 s-2)
... G = 6.67300E-11
... return G * self.mass / (self.radius * self.radius)
...
>>> Planet.EARTH.value
(5.976e+24, 6378140.0)
>>> Planet.EARTH.surface_gravity
9.802652743337129
```
### TimePeriod
An example to show the `_ignore_` attribute in use:
```
>>> from datetime import timedelta
>>> class Period(timedelta, Enum):
... "different lengths of time"
... _ignore_ = 'Period i'
... Period = vars()
... for i in range(367):
... Period['day_%d' % i] = i
...
>>> list(Period)[:2]
[<Period.day_0: datetime.timedelta(0)>, <Period.day_1: datetime.timedelta(days=1)>]
>>> list(Period)[-2:]
[<Period.day_365: datetime.timedelta(days=365)>, <Period.day_366: datetime.timedelta(days=366)>]
```
## How are Enums different?
Enums have a custom metaclass that affects many aspects of both derived Enum classes and their instances (members).
### Enum Classes
The `EnumMeta` metaclass is responsible for providing the [`__contains__()`](../reference/datamodel.xhtml#object.__contains__ "object.__contains__"), [`__dir__()`](../reference/datamodel.xhtml#object.__dir__ "object.__dir__"), [`__iter__()`](../reference/datamodel.xhtml#object.__iter__ "object.__iter__") and other methods that allow one to do things with an [`Enum`](#enum.Enum "enum.Enum") class that fail on a typical class, such as list(Color) or some\_enum\_var in Color. `EnumMeta` is responsible for ensuring that various other methods on the final [`Enum`](#enum.Enum "enum.Enum")class are correct (such as [`__new__()`](../reference/datamodel.xhtml#object.__new__ "object.__new__"), [`__getnewargs__()`](pickle.xhtml#object.__getnewargs__ "object.__getnewargs__"), [`__str__()`](../reference/datamodel.xhtml#object.__str__ "object.__str__") and [`__repr__()`](../reference/datamodel.xhtml#object.__repr__ "object.__repr__")).
### Enum Members (aka instances)
The most interesting thing about Enum members is that they are singletons. `EnumMeta` creates them all while it is creating the [`Enum`](#enum.Enum "enum.Enum")class itself, and then puts a custom [`__new__()`](../reference/datamodel.xhtml#object.__new__ "object.__new__") in place to ensure that no new ones are ever instantiated by returning only the existing member instances.
### Finer Points
#### Supported `__dunder__` names
`__members__` is an `OrderedDict` of `member_name`:`member`items. It is only available on the class.
[`__new__()`](../reference/datamodel.xhtml#object.__new__ "object.__new__"), if specified, must create and return the enum members; it is also a very good idea to set the member's `_value_` appropriately. Once all the members are created it is no longer used.
#### Supported `_sunder_` names
- `_name_` -- name of the member
- `_value_` -- value of the member; can be set / modified in `__new__`
- `_missing_` -- a lookup function used when a value is not found; may be overridden
- `_ignore_` -- a list of names, either as a [`list()`](stdtypes.xhtml#list "list") or a [`str()`](stdtypes.xhtml#str "str"), that will not be transformed into members, and will be removed from the final class
- `_order_` -- used in Python 2/3 code to ensure member order is consistent (class attribute, removed during class creation)
- `_generate_next_value_` -- used by the [Functional API](#functional-api) and by [`auto`](#enum.auto "enum.auto") to get an appropriate value for an enum member; may be overridden
3\.6 新版功能: `_missing_`, `_order_`, `_generate_next_value_`
3\.7 新版功能: `_ignore_`
To help keep Python 2 / Python 3 code in sync an `_order_` attribute can be provided. It will be checked against the actual order of the enumeration and raise an error if the two do not match:
```
>>> class Color(Enum):
... _order_ = 'RED GREEN BLUE'
... RED = 1
... BLUE = 3
... GREEN = 2
...
Traceback (most recent call last):
...
TypeError: member order does not match _order_
```
注解
In Python 2 code the `_order_` attribute is necessary as definition order is lost before it can be recorded.
#### `Enum` member type
[`Enum`](#enum.Enum "enum.Enum") members are instances of their [`Enum`](#enum.Enum "enum.Enum") class, and are normally accessed as `EnumClass.member`. Under certain circumstances they can also be accessed as `EnumClass.member.member`, but you should never do this as that lookup may fail or, worse, return something besides the [`Enum`](#enum.Enum "enum.Enum") member you are looking for (this is another good reason to use all-uppercase names for members):
```
>>> class FieldTypes(Enum):
... name = 0
... value = 1
... size = 2
...
>>> FieldTypes.value.size
<FieldTypes.size: 2>
>>> FieldTypes.size.value
2
```
在 3.5 版更改.
#### Boolean value of `Enum` classes and members
[`Enum`](#enum.Enum "enum.Enum") members that are mixed with non-[`Enum`](#enum.Enum "enum.Enum") types (such as [`int`](functions.xhtml#int "int"), [`str`](stdtypes.xhtml#str "str"), etc.) are evaluated according to the mixed-in type's rules; otherwise, all members evaluate as [`True`](constants.xhtml#True "True"). To make your own Enum's boolean evaluation depend on the member's value add the following to your class:
```
def __bool__(self):
return bool(self.value)
```
[`Enum`](#enum.Enum "enum.Enum") classes always evaluate as [`True`](constants.xhtml#True "True").
#### `Enum` classes with methods
If you give your [`Enum`](#enum.Enum "enum.Enum") subclass extra methods, like the [Planet](#planet)class above, those methods will show up in a [`dir()`](functions.xhtml#dir "dir") of the member, but not of the class:
```
>>> dir(Planet)
['EARTH', 'JUPITER', 'MARS', 'MERCURY', 'NEPTUNE', 'SATURN', 'URANUS', 'VENUS', '__class__', '__doc__', '__members__', '__module__']
>>> dir(Planet.EARTH)
['__class__', '__doc__', '__module__', 'name', 'surface_gravity', 'value']
```
#### Combining members of `Flag`
If a combination of Flag members is not named, the [`repr()`](functions.xhtml#repr "repr") will include all named flags and all named combinations of flags that are in the value:
```
>>> class Color(Flag):
... RED = auto()
... GREEN = auto()
... BLUE = auto()
... MAGENTA = RED | BLUE
... YELLOW = RED | GREEN
... CYAN = GREEN | BLUE
...
>>> Color(3) # named combination
<Color.YELLOW: 3>
>>> Color(7) # not named combination
<Color.CYAN|MAGENTA|BLUE|YELLOW|GREEN|RED: 7>
```
### 导航
- [索引](../genindex.xhtml "总目录")
- [模块](../py-modindex.xhtml "Python 模块索引") |
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- 安装和使用 Python
- 命令行与环境
- 命令行
- 环境变量
- 在Unix平台中使用Python
- 获取最新版本的Python
- 构建Python
- 与Python相关的路径和文件
- 杂项
- 编辑器和集成开发环境
- 在Windows上使用 Python
- 完整安装程序
- Microsoft Store包
- nuget.org 安装包
- 可嵌入的包
- 替代捆绑包
- 配置Python
- 适用于Windows的Python启动器
- 查找模块
- 附加模块
- 在Windows上编译Python
- 其他平台
- 在苹果系统上使用 Python
- 获取和安装 MacPython
- IDE
- 安装额外的 Python 包
- Mac 上的图形界面编程
- 在 Mac 上分发 Python 应用程序
- 其他资源
- Python 语言参考
- 概述
- 其他实现
- 标注
- 词法分析
- 行结构
- 其他形符
- 标识符和关键字
- 字面值
- 运算符
- 分隔符
- 数据模型
- 对象、值与类型
- 标准类型层级结构
- 特殊方法名称
- 协程
- 执行模型
- 程序的结构
- 命名与绑定
- 异常
- 导入系统
- importlib
- 包
- 搜索
- 加载
- 基于路径的查找器
- 替换标准导入系统
- Package Relative Imports
- 有关 main 的特殊事项
- 开放问题项
- 参考文献
- 表达式
- 算术转换
- 原子
- 原型
- await 表达式
- 幂运算符
- 一元算术和位运算
- 二元算术运算符
- 移位运算
- 二元位运算
- 比较运算
- 布尔运算
- 条件表达式
- lambda 表达式
- 表达式列表
- 求值顺序
- 运算符优先级
- 简单语句
- 表达式语句
- 赋值语句
- assert 语句
- pass 语句
- del 语句
- return 语句
- yield 语句
- raise 语句
- break 语句
- continue 语句
- import 语句
- global 语句
- nonlocal 语句
- 复合语句
- if 语句
- while 语句
- for 语句
- try 语句
- with 语句
- 函数定义
- 类定义
- 协程
- 最高层级组件
- 完整的 Python 程序
- 文件输入
- 交互式输入
- 表达式输入
- 完整的语法规范
- Python 标准库
- 概述
- 可用性注释
- 内置函数
- 内置常量
- 由 site 模块添加的常量
- 内置类型
- 逻辑值检测
- 布尔运算 — and, or, not
- 比较
- 数字类型 — int, float, complex
- 迭代器类型
- 序列类型 — list, tuple, range
- 文本序列类型 — str
- 二进制序列类型 — bytes, bytearray, memoryview
- 集合类型 — set, frozenset
- 映射类型 — dict
- 上下文管理器类型
- 其他内置类型
- 特殊属性
- 内置异常
- 基类
- 具体异常
- 警告
- 异常层次结构
- 文本处理服务
- string — 常见的字符串操作
- re — 正则表达式操作
- 模块 difflib 是一个计算差异的助手
- textwrap — Text wrapping and filling
- unicodedata — Unicode 数据库
- stringprep — Internet String Preparation
- readline — GNU readline interface
- rlcompleter — GNU readline的完成函数
- 二进制数据服务
- struct — Interpret bytes as packed binary data
- codecs — Codec registry and base classes
- 数据类型
- datetime — 基础日期/时间数据类型
- calendar — General calendar-related functions
- collections — 容器数据类型
- collections.abc — 容器的抽象基类
- heapq — 堆队列算法
- bisect — Array bisection algorithm
- array — Efficient arrays of numeric values
- weakref — 弱引用
- types — Dynamic type creation and names for built-in types
- copy — 浅层 (shallow) 和深层 (deep) 复制操作
- pprint — 数据美化输出
- reprlib — Alternate repr() implementation
- enum — Support for enumerations
- 数字和数学模块
- numbers — 数字的抽象基类
- math — 数学函数
- cmath — Mathematical functions for complex numbers
- decimal — 十进制定点和浮点运算
- fractions — 分数
- random — 生成伪随机数
- statistics — Mathematical statistics functions
- 函数式编程模块
- itertools — 为高效循环而创建迭代器的函数
- functools — 高阶函数和可调用对象上的操作
- operator — 标准运算符替代函数
- 文件和目录访问
- pathlib — 面向对象的文件系统路径
- os.path — 常见路径操作
- fileinput — Iterate over lines from multiple input streams
- stat — Interpreting stat() results
- filecmp — File and Directory Comparisons
- tempfile — Generate temporary files and directories
- glob — Unix style pathname pattern expansion
- fnmatch — Unix filename pattern matching
- linecache — Random access to text lines
- shutil — High-level file operations
- macpath — Mac OS 9 路径操作函数
- 数据持久化
- pickle —— Python 对象序列化
- copyreg — Register pickle support functions
- shelve — Python object persistence
- marshal — Internal Python object serialization
- dbm — Interfaces to Unix “databases”
- sqlite3 — SQLite 数据库 DB-API 2.0 接口模块
- 数据压缩和存档
- zlib — 与 gzip 兼容的压缩
- gzip — 对 gzip 格式的支持
- bz2 — 对 bzip2 压缩算法的支持
- lzma — 用 LZMA 算法压缩
- zipfile — 在 ZIP 归档中工作
- tarfile — Read and write tar archive files
- 文件格式
- csv — CSV 文件读写
- configparser — Configuration file parser
- netrc — netrc file processing
- xdrlib — Encode and decode XDR data
- plistlib — Generate and parse Mac OS X .plist files
- 加密服务
- hashlib — 安全哈希与消息摘要
- hmac — 基于密钥的消息验证
- secrets — Generate secure random numbers for managing secrets
- 通用操作系统服务
- os — 操作系统接口模块
- io — 处理流的核心工具
- time — 时间的访问和转换
- argparse — 命令行选项、参数和子命令解析器
- getopt — C-style parser for command line options
- 模块 logging — Python 的日志记录工具
- logging.config — 日志记录配置
- logging.handlers — Logging handlers
- getpass — 便携式密码输入工具
- curses — 终端字符单元显示的处理
- curses.textpad — Text input widget for curses programs
- curses.ascii — Utilities for ASCII characters
- curses.panel — A panel stack extension for curses
- platform — Access to underlying platform's identifying data
- errno — Standard errno system symbols
- ctypes — Python 的外部函数库
- 并发执行
- threading — 基于线程的并行
- multiprocessing — 基于进程的并行
- concurrent 包
- concurrent.futures — 启动并行任务
- subprocess — 子进程管理
- sched — 事件调度器
- queue — 一个同步的队列类
- _thread — 底层多线程 API
- _dummy_thread — _thread 的替代模块
- dummy_threading — 可直接替代 threading 模块。
- contextvars — Context Variables
- Context Variables
- Manual Context Management
- asyncio support
- 网络和进程间通信
- asyncio — 异步 I/O
- socket — 底层网络接口
- ssl — TLS/SSL wrapper for socket objects
- select — Waiting for I/O completion
- selectors — 高级 I/O 复用库
- asyncore — 异步socket处理器
- asynchat — 异步 socket 指令/响应 处理器
- signal — Set handlers for asynchronous events
- mmap — Memory-mapped file support
- 互联网数据处理
- email — 电子邮件与 MIME 处理包
- json — JSON 编码和解码器
- mailcap — Mailcap file handling
- mailbox — Manipulate mailboxes in various formats
- mimetypes — Map filenames to MIME types
- base64 — Base16, Base32, Base64, Base85 数据编码
- binhex — 对binhex4文件进行编码和解码
- binascii — 二进制和 ASCII 码互转
- quopri — Encode and decode MIME quoted-printable data
- uu — Encode and decode uuencode files
- 结构化标记处理工具
- html — 超文本标记语言支持
- html.parser — 简单的 HTML 和 XHTML 解析器
- html.entities — HTML 一般实体的定义
- XML处理模块
- xml.etree.ElementTree — The ElementTree XML API
- xml.dom — The Document Object Model API
- xml.dom.minidom — Minimal DOM implementation
- xml.dom.pulldom — Support for building partial DOM trees
- xml.sax — Support for SAX2 parsers
- xml.sax.handler — Base classes for SAX handlers
- xml.sax.saxutils — SAX Utilities
- xml.sax.xmlreader — Interface for XML parsers
- xml.parsers.expat — Fast XML parsing using Expat
- 互联网协议和支持
- webbrowser — 方便的Web浏览器控制器
- cgi — Common Gateway Interface support
- cgitb — Traceback manager for CGI scripts
- wsgiref — WSGI Utilities and Reference Implementation
- urllib — URL 处理模块
- urllib.request — 用于打开 URL 的可扩展库
- urllib.response — Response classes used by urllib
- urllib.parse — Parse URLs into components
- urllib.error — Exception classes raised by urllib.request
- urllib.robotparser — Parser for robots.txt
- http — HTTP 模块
- http.client — HTTP协议客户端
- ftplib — FTP protocol client
- poplib — POP3 protocol client
- imaplib — IMAP4 protocol client
- nntplib — NNTP protocol client
- smtplib —SMTP协议客户端
- smtpd — SMTP Server
- telnetlib — Telnet client
- uuid — UUID objects according to RFC 4122
- socketserver — A framework for network servers
- http.server — HTTP 服务器
- http.cookies — HTTP state management
- http.cookiejar — Cookie handling for HTTP clients
- xmlrpc — XMLRPC 服务端与客户端模块
- xmlrpc.client — XML-RPC client access
- xmlrpc.server — Basic XML-RPC servers
- ipaddress — IPv4/IPv6 manipulation library
- 多媒体服务
- audioop — Manipulate raw audio data
- aifc — Read and write AIFF and AIFC files
- sunau — 读写 Sun AU 文件
- wave — 读写WAV格式文件
- chunk — Read IFF chunked data
- colorsys — Conversions between color systems
- imghdr — 推测图像类型
- sndhdr — 推测声音文件的类型
- ossaudiodev — Access to OSS-compatible audio devices
- 国际化
- gettext — 多语种国际化服务
- locale — 国际化服务
- 程序框架
- turtle — 海龟绘图
- cmd — 支持面向行的命令解释器
- shlex — Simple lexical analysis
- Tk图形用户界面(GUI)
- tkinter — Tcl/Tk的Python接口
- tkinter.ttk — Tk themed widgets
- tkinter.tix — Extension widgets for Tk
- tkinter.scrolledtext — 滚动文字控件
- IDLE
- 其他图形用户界面（GUI）包
- 开发工具
- typing — 类型标注支持
- pydoc — Documentation generator and online help system
- doctest — Test interactive Python examples
- unittest — 单元测试框架
- unittest.mock — mock object library
- unittest.mock 上手指南
- 2to3 - 自动将 Python 2 代码转为 Python 3 代码
- test — Regression tests package for Python
- test.support — Utilities for the Python test suite
- test.support.script_helper — Utilities for the Python execution tests
- 调试和分析
- bdb — Debugger framework
- faulthandler — Dump the Python traceback
- pdb — The Python Debugger
- The Python Profilers
- timeit — 测量小代码片段的执行时间
- trace — Trace or track Python statement execution
- tracemalloc — Trace memory allocations
- 软件打包和分发
- distutils — 构建和安装 Python 模块
- ensurepip — Bootstrapping the pip installer
- venv — 创建虚拟环境
- zipapp — Manage executable Python zip archives
- Python运行时服务
- sys — 系统相关的参数和函数
- sysconfig — Provide access to Python's configuration information
- builtins — 内建对象
- main — 顶层脚本环境
- warnings — Warning control
- dataclasses — 数据类
- contextlib — Utilities for with-statement contexts
- abc — 抽象基类
- atexit — 退出处理器
- traceback — Print or retrieve a stack traceback
- future — Future 语句定义
- gc — 垃圾回收器接口
- inspect — 检查对象
- site — Site-specific configuration hook
- 自定义 Python 解释器
- code — Interpreter base classes
- codeop — Compile Python code
- 导入模块
- zipimport — Import modules from Zip archives
- pkgutil — Package extension utility
- modulefinder — 查找脚本使用的模块
- runpy — Locating and executing Python modules
- importlib — The implementation of import
- Python 语言服务
- parser — Access Python parse trees
- ast — 抽象语法树
- symtable — Access to the compiler's symbol tables
- symbol — 与 Python 解析树一起使用的常量
- token — 与Python解析树一起使用的常量
- keyword — 检验Python关键字
- tokenize — Tokenizer for Python source
- tabnanny — 模糊缩进检测
- pyclbr — Python class browser support
- py_compile — Compile Python source files
- compileall — Byte-compile Python libraries
- dis — Python 字节码反汇编器
- pickletools — Tools for pickle developers
- 杂项服务
- formatter — Generic output formatting
- Windows系统相关模块
- msilib — Read and write Microsoft Installer files
- msvcrt — Useful routines from the MS VC++ runtime
- winreg — Windows 注册表访问
- winsound — Sound-playing interface for Windows
- Unix 专有服务
- posix — The most common POSIX system calls
- pwd — 用户密码数据库
- spwd — The shadow password database
- grp — The group database
- crypt — Function to check Unix passwords
- termios — POSIX style tty control
- tty — 终端控制功能
- pty — Pseudo-terminal utilities
- fcntl — The fcntl and ioctl system calls
- pipes — Interface to shell pipelines
- resource — Resource usage information
- nis — Interface to Sun's NIS (Yellow Pages)
- Unix syslog 库例程
- 被取代的模块
- optparse — Parser for command line options
- imp — Access the import internals
- 未创建文档的模块
- 平台特定模块
- 扩展和嵌入 Python 解释器
- 推荐的第三方工具
- 不使用第三方工具创建扩展
- 使用 C 或 C++ 扩展 Python
- 自定义扩展类型：教程
- 定义扩展类型：已分类主题
- 构建C/C++扩展
- 在Windows平台编译C和C++扩展
- 在更大的应用程序中嵌入 CPython 运行时
- Embedding Python in Another Application
- Python/C API 参考手册
- 概述
- 代码标准
- 包含文件
- 有用的宏
- 对象、类型和引用计数
- 异常
- 嵌入Python
- 调试构建
- 稳定的应用程序二进制接口
- The Very High Level Layer
- Reference Counting
- 异常处理
- Printing and clearing
- 抛出异常
- Issuing warnings
- Querying the error indicator
- Signal Handling
- Exception Classes
- Exception Objects
- Unicode Exception Objects
- Recursion Control
- 标准异常
- 标准警告类别
- 工具
- 操作系统实用程序
- 系统功能
- 过程控制
- 导入模块
- Data marshalling support
- 语句解释及变量编译
- 字符串转换与格式化
- 反射
- 编解码器注册与支持功能
- 抽象对象层
- Object Protocol
- 数字协议
- Sequence Protocol
- Mapping Protocol
- 迭代器协议
- 缓冲协议
- Old Buffer Protocol
- 具体的对象层
- 基本对象
- 数值对象
- 序列对象
- 容器对象
- 函数对象
- 其他对象
- Initialization, Finalization, and Threads
- 在Python初始化之前
- 全局配置变量
- Initializing and finalizing the interpreter
- Process-wide parameters
- Thread State and the Global Interpreter Lock
- Sub-interpreter support
- Asynchronous Notifications
- Profiling and Tracing
- Advanced Debugger Support
- Thread Local Storage Support
- 内存管理
- 概述
- 原始内存接口
- Memory Interface
- 对象分配器
- 默认内存分配器
- Customize Memory Allocators
- The pymalloc allocator
- tracemalloc C API
- 示例
- 对象实现支持
- 在堆中分配对象
- Common Object Structures
- Type 对象
- Number Object Structures
- Mapping Object Structures
- Sequence Object Structures
- Buffer Object Structures
- Async Object Structures
- 使对象类型支持循环垃圾回收
- API 和 ABI 版本管理
- 分发 Python 模块
- 关键术语
- 开源许可与协作
- 安装工具
- 阅读指南
- 我该如何...？
- ...为我的项目选择一个名字？
- ...创建和分发二进制扩展？
- 安装 Python 模块
- 关键术语
- 基本使用
- 我应如何 ...？
- ... 在 Python 3.4 之前的 Python 版本中安装 pip ？
- ... 只为当前用户安装软件包？
- ... 安装科学计算类 Python 软件包？
- ... 使用并行安装的多个 Python 版本？
- 常见的安装问题
- 在 Linux 的系统 Python 版本上安装
- 未安装 pip
- 安装二进制编译扩展
- Python 常用指引
- 将 Python 2 代码迁移到 Python 3
- 简要说明
- 详情
- 将扩展模块移植到 Python 3
- 条件编译
- 对象API的更改
- 模块初始化和状态
- CObject 替换为 Capsule
- 其他选项
- Curses Programming with Python
- What is curses?
- Starting and ending a curses application
- Windows and Pads
- Displaying Text
- User Input
- For More Information
- 实现描述器
- 摘要
- 定义和简介
- 描述器协议
- 发起调用描述符
- 描述符示例
- Properties
- 函数和方法
- Static Methods and Class Methods
- 函数式编程指引
- 概述
- 迭代器
- 生成器表达式和列表推导式
- 生成器
- 内置函数
- itertools 模块
- The functools module
- Small functions and the lambda expression
- Revision History and Acknowledgements
- 引用文献
- 日志 HOWTO
- 日志基础教程
- 进阶日志教程
- 日志级别
- 有用的处理程序
- 记录日志中引发的异常
- 使用任意对象作为消息
- 优化
- 日志操作手册
- 在多个模块中使用日志
- 在多线程中使用日志
- 使用多个日志处理器和多种格式化
- 在多个地方记录日志
- 日志服务器配置示例
- 处理日志处理器的阻塞
- Sending and receiving logging events across a network
- Adding contextual information to your logging output
- Logging to a single file from multiple processes
- Using file rotation
- Use of alternative formatting styles
- Customizing LogRecord
- Subclassing QueueHandler - a ZeroMQ example
- Subclassing QueueListener - a ZeroMQ example
- An example dictionary-based configuration
- Using a rotator and namer to customize log rotation processing
- A more elaborate multiprocessing example
- Inserting a BOM into messages sent to a SysLogHandler
- Implementing structured logging
- Customizing handlers with dictConfig()
- Using particular formatting styles throughout your application
- Configuring filters with dictConfig()
- Customized exception formatting
- Speaking logging messages
- Buffering logging messages and outputting them conditionally
- Formatting times using UTC (GMT) via configuration
- Using a context manager for selective logging
- 正则表达式HOWTO
- 概述
- 简单模式
- 使用正则表达式
- 更多模式能力
- 修改字符串
- 常见问题
- 反馈
- 套接字编程指南
- 套接字
- 创建套接字
- 使用一个套接字
- 断开连接
- 非阻塞的套接字
- 排序指南
- 基本排序
- 关键函数
- Operator 模块函数
- 升序和降序
- 排序稳定性和排序复杂度
- 使用装饰-排序-去装饰的旧方法
- 使用 cmp 参数的旧方法
- 其它
- Unicode 指南
- Unicode 概述
- Python's Unicode Support
- Reading and Writing Unicode Data
- Acknowledgements
- 如何使用urllib包获取网络资源
- 概述
- Fetching URLs
- 处理异常
- info and geturl
- Openers and Handlers
- Basic Authentication
- Proxies
- Sockets and Layers
- 脚注
- Argparse 教程
- 概念
- 基础
- 位置参数介绍
- Introducing Optional arguments
- Combining Positional and Optional arguments
- Getting a little more advanced
- Conclusion
- ipaddress模块介绍
- 创建 Address/Network/Interface 对象
- 审查 Address/Network/Interface 对象
- Network 作为 Address 列表
- 比较
- 将IP地址与其他模块一起使用
- 实例创建失败时获取更多详细信息
- Argument Clinic How-To
- The Goals Of Argument Clinic
- Basic Concepts And Usage
- Converting Your First Function
- Advanced Topics
- 使用 DTrace 和 SystemTap 检测CPython
- Enabling the static markers
- Static DTrace probes
- Static SystemTap markers
- Available static markers
- SystemTap Tapsets
- 示例
- Python 常见问题
- Python常见问题
- 一般信息
- 现实世界中的 Python
- 编程常见问题
- 一般问题
- 核心语言
- 数字和字符串
- 性能
- 序列（元组/列表）
- 对象
- 模块
- 设计和历史常见问题
- 为什么Python使用缩进来分组语句？
- 为什么简单的算术运算得到奇怪的结果？
- 为什么浮点计算不准确？
- 为什么Python字符串是不可变的？
- 为什么必须在方法定义和调用中显式使用“self”？
- 为什么不能在表达式中赋值？
- 为什么Python对某些功能（例如list.index()）使用方法来实现，而其他功能（例如len(List)）使用函数实现？
- 为什么 join()是一个字符串方法而不是列表或元组方法？
- 异常有多快？
- 为什么Python中没有switch或case语句？
- 难道不能在解释器中模拟线程，而非得依赖特定于操作系统的线程实现吗？
- 为什么lambda表达式不能包含语句？
- 可以将Python编译为机器代码，C或其他语言吗？
- Python如何管理内存？
- 为什么CPython不使用更传统的垃圾回收方案？
- CPython退出时为什么不释放所有内存？
- 为什么有单独的元组和列表数据类型？
- 列表是如何在CPython中实现的？
- 字典是如何在CPython中实现的？
- 为什么字典key必须是不可变的？
- 为什么 list.sort() 没有返回排序列表？
- 如何在Python中指定和实施接口规范？
- 为什么没有goto？
- 为什么原始字符串（r-strings）不能以反斜杠结尾？
- 为什么Python没有属性赋值的“with”语句？
- 为什么 if/while/def/class语句需要冒号？
- 为什么Python在列表和元组的末尾允许使用逗号？
- 代码库和插件 FAQ
- 通用的代码库问题
- 通用任务
- 线程相关
- 输入输出
- 网络 / Internet 编程
- 数据库
- 数学和数字
- 扩展/嵌入常见问题
- 可以使用C语言中创建自己的函数吗？
- 可以使用C++语言中创建自己的函数吗？
- C很难写，有没有其他选择？
- 如何从C执行任意Python语句？
- 如何从C中评估任意Python表达式？
- 如何从Python对象中提取C的值？
- 如何使用Py_BuildValue()创建任意长度的元组？
- 如何从C调用对象的方法？
- 如何捕获PyErr_Print()（或打印到stdout / stderr的任何内容）的输出？
- 如何从C访问用Python编写的模块？
- 如何从Python接口到C ++对象？
- 我使用Setup文件添加了一个模块，为什么make失败了？
- 如何调试扩展？
- 我想在Linux系统上编译一个Python模块，但是缺少一些文件。为什么?
- 如何区分“输入不完整”和“输入无效”？
- 如何找到未定义的g++符号__builtin_new或__pure_virtual？
- 能否创建一个对象类，其中部分方法在C中实现，而其他方法在Python中实现（例如通过继承）？
- Python在Windows上的常见问题
- 我怎样在Windows下运行一个Python程序？
- 我怎么让 Python 脚本可执行？
- 为什么有时候 Python 程序会启动缓慢？
- 我怎样使用Python脚本制作可执行文件？
- *.pyd 文件和DLL文件相同吗？
- 我怎样将Python嵌入一个Windows程序？
- 如何让编辑器不要在我的 Python 源代码中插入 tab ？
- 如何在不阻塞的情况下检查按键？
- 图形用户界面（GUI）常见问题
- 图形界面常见问题
- Python 是否有平台无关的图形界面工具包？
- 有哪些Python的GUI工具是某个平台专用的？
- 有关Tkinter的问题
- “为什么我的电脑上安装了 Python ？”
- 什么是Python？
- 为什么我的电脑上安装了 Python ？
- 我能删除 Python 吗？
- 术语对照表
- 文档说明
- Python 文档贡献者
- 解决 Bug
- 文档错误
- 使用 Python 的错误追踪系统
- 开始为 Python 贡献您的知识
- 版权
- 历史和许可证
- 软件历史
- 访问Python或以其他方式使用Python的条款和条件
- Python 3.7.3 的 PSF 许可协议
- Python 2.0 的 BeOpen.com 许可协议
- Python 1.6.1 的 CNRI 许可协议
- Python 0.9.0 至 1.2 的 CWI 许可协议
- 集成软件的许可和认可
- Mersenne Twister
- 套接字
- Asynchronous socket services
- Cookie management
- Execution tracing
- UUencode and UUdecode functions
- XML Remote Procedure Calls
- test_epoll
- Select kqueue
- SipHash24
- strtod and dtoa
- OpenSSL
- expat
- libffi
- zlib
- cfuhash
- libmpdec