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# Type 对象
Perhaps one of the most important structures of the Python object system is the structure that defines a new type: the [`PyTypeObject`](type.xhtml#c.PyTypeObject "PyTypeObject") structure. Type objects can be handled using any of the `PyObject_*()` or `PyType_*()` functions, but do not offer much that's interesting to most Python applications. These objects are fundamental to how objects behave, so they are very important to the interpreter itself and to any extension module that implements new types.
Type objects are fairly large compared to most of the standard types. The reason for the size is that each type object stores a large number of values, mostly C function pointers, each of which implements a small part of the type's functionality. The fields of the type object are examined in detail in this section. The fields will be described in the order in which they occur in the structure.
Typedefs: unaryfunc, binaryfunc, ternaryfunc, inquiry, intargfunc, intintargfunc, intobjargproc, intintobjargproc, objobjargproc, destructor, freefunc, printfunc, getattrfunc, getattrofunc, setattrfunc, setattrofunc, reprfunc, hashfunc
The structure definition for [`PyTypeObject`](type.xhtml#c.PyTypeObject "PyTypeObject") can be found in `Include/object.h`. For convenience of reference, this repeats the definition found there:
```
typedef struct _typeobject {
PyObject_VAR_HEAD
const char *tp_name; /* For printing, in format "<module>.<name>" */
Py_ssize_t tp_basicsize, tp_itemsize; /* For allocation */
/* Methods to implement standard operations */
destructor tp_dealloc;
printfunc tp_print;
getattrfunc tp_getattr;
setattrfunc tp_setattr;
PyAsyncMethods *tp_as_async; /* formerly known as tp_compare (Python 2)
or tp_reserved (Python 3) */
reprfunc tp_repr;
/* Method suites for standard classes */
PyNumberMethods *tp_as_number;
PySequenceMethods *tp_as_sequence;
PyMappingMethods *tp_as_mapping;
/* More standard operations (here for binary compatibility) */
hashfunc tp_hash;
ternaryfunc tp_call;
reprfunc tp_str;
getattrofunc tp_getattro;
setattrofunc tp_setattro;
/* Functions to access object as input/output buffer */
PyBufferProcs *tp_as_buffer;
/* Flags to define presence of optional/expanded features */
unsigned long tp_flags;
const char *tp_doc; /* Documentation string */
/* call function for all accessible objects */
traverseproc tp_traverse;
/* delete references to contained objects */
inquiry tp_clear;
/* rich comparisons */
richcmpfunc tp_richcompare;
/* weak reference enabler */
Py_ssize_t tp_weaklistoffset;
/* Iterators */
getiterfunc tp_iter;
iternextfunc tp_iternext;
/* Attribute descriptor and subclassing stuff */
struct PyMethodDef *tp_methods;
struct PyMemberDef *tp_members;
struct PyGetSetDef *tp_getset;
struct _typeobject *tp_base;
PyObject *tp_dict;
descrgetfunc tp_descr_get;
descrsetfunc tp_descr_set;
Py_ssize_t tp_dictoffset;
initproc tp_init;
allocfunc tp_alloc;
newfunc tp_new;
freefunc tp_free; /* Low-level free-memory routine */
inquiry tp_is_gc; /* For PyObject_IS_GC */
PyObject *tp_bases;
PyObject *tp_mro; /* method resolution order */
PyObject *tp_cache;
PyObject *tp_subclasses;
PyObject *tp_weaklist;
destructor tp_del;
/* Type attribute cache version tag. Added in version 2.6 */
unsigned int tp_version_tag;
destructor tp_finalize;
} PyTypeObject;
```
The type object structure extends the [`PyVarObject`](structures.xhtml#c.PyVarObject "PyVarObject") structure. The `ob_size` field is used for dynamic types (created by `type_new()`, usually called from a class statement). Note that [`PyType_Type`](type.xhtml#c.PyType_Type "PyType_Type") (the metatype) initializes [`tp_itemsize`](#c.PyTypeObject.tp_itemsize "PyTypeObject.tp_itemsize"), which means that its instances (i.e. type objects) *must* have the `ob_size` field.
[PyObject](structures.xhtml#c.PyObject "PyObject")\* `PyObject._ob_next`[PyObject](structures.xhtml#c.PyObject "PyObject")\* `PyObject._ob_prev`These fields are only present when the macro `Py_TRACE_REFS` is defined. Their initialization to *NULL* is taken care of by the `PyObject_HEAD_INIT`macro. For statically allocated objects, these fields always remain *NULL*. For dynamically allocated objects, these two fields are used to link the object into a doubly-linked list of *all* live objects on the heap. This could be used for various debugging purposes; currently the only use is to print the objects that are still alive at the end of a run when the environment variable [`PYTHONDUMPREFS`](../using/cmdline.xhtml#envvar-PYTHONDUMPREFS) is set.
These fields are not inherited by subtypes.
Py\_ssize\_t `PyObject.ob_refcnt`This is the type object's reference count, initialized to `1` by the `PyObject_HEAD_INIT` macro. Note that for statically allocated type objects, the type's instances (objects whose `ob_type` points back to the type) do *not* count as references. But for dynamically allocated type objects, the instances *do* count as references.
This field is not inherited by subtypes.
[PyTypeObject](type.xhtml#c.PyTypeObject "PyTypeObject")\* `PyObject.ob_type`This is the type's type, in other words its metatype. It is initialized by the argument to the `PyObject_HEAD_INIT` macro, and its value should normally be `&PyType_Type`. However, for dynamically loadable extension modules that must be usable on Windows (at least), the compiler complains that this is not a valid initializer. Therefore, the convention is to pass *NULL* to the `PyObject_HEAD_INIT` macro and to initialize this field explicitly at the start of the module's initialization function, before doing anything else. This is typically done like this:
```
Foo_Type.ob_type = &PyType_Type;
```
This should be done before any instances of the type are created. [`PyType_Ready()`](type.xhtml#c.PyType_Ready "PyType_Ready") checks if `ob_type` is *NULL*, and if so, initializes it to the `ob_type` field of the base class. [`PyType_Ready()`](type.xhtml#c.PyType_Ready "PyType_Ready") will not change this field if it is non-zero.
This field is inherited by subtypes.
Py\_ssize\_t `PyVarObject.ob_size`For statically allocated type objects, this should be initialized to zero. For dynamically allocated type objects, this field has a special internal meaning.
This field is not inherited by subtypes.
const char\* `PyTypeObject.tp_name`Pointer to a NUL-terminated string containing the name of the type. For types that are accessible as module globals, the string should be the full module name, followed by a dot, followed by the type name; for built-in types, it should be just the type name. If the module is a submodule of a package, the full package name is part of the full module name. For example, a type named `T` defined in module `M` in subpackage `Q` in package `P`should have the [`tp_name`](#c.PyTypeObject.tp_name "PyTypeObject.tp_name") initializer `"P.Q.M.T"`.
For dynamically allocated type objects, this should just be the type name, and the module name explicitly stored in the type dict as the value for key `'__module__'`.
For statically allocated type objects, the tp\_name field should contain a dot. Everything before the last dot is made accessible as the `__module__`attribute, and everything after the last dot is made accessible as the [`__name__`](../library/stdtypes.xhtml#definition.__name__ "definition.__name__") attribute.
If no dot is present, the entire [`tp_name`](#c.PyTypeObject.tp_name "PyTypeObject.tp_name") field is made accessible as the [`__name__`](../library/stdtypes.xhtml#definition.__name__ "definition.__name__") attribute, and the `__module__` attribute is undefined (unless explicitly set in the dictionary, as explained above). This means your type will be impossible to pickle. Additionally, it will not be listed in module documentations created with pydoc.
This field is not inherited by subtypes.
Py\_ssize\_t `PyTypeObject.tp_basicsize`Py\_ssize\_t `PyTypeObject.tp_itemsize`These fields allow calculating the size in bytes of instances of the type.
There are two kinds of types: types with fixed-length instances have a zero [`tp_itemsize`](#c.PyTypeObject.tp_itemsize "PyTypeObject.tp_itemsize") field, types with variable-length instances have a non-zero [`tp_itemsize`](#c.PyTypeObject.tp_itemsize "PyTypeObject.tp_itemsize") field. For a type with fixed-length instances, all instances have the same size, given in [`tp_basicsize`](#c.PyTypeObject.tp_basicsize "PyTypeObject.tp_basicsize").
For a type with variable-length instances, the instances must have an `ob_size` field, and the instance size is [`tp_basicsize`](#c.PyTypeObject.tp_basicsize "PyTypeObject.tp_basicsize") plus N times [`tp_itemsize`](#c.PyTypeObject.tp_itemsize "PyTypeObject.tp_itemsize"), where N is the "length" of the object. The value of N is typically stored in the instance's `ob_size` field. There are exceptions: for example, ints use a negative `ob_size` to indicate a negative number, and N is `abs(ob_size)` there. Also, the presence of an `ob_size` field in the instance layout doesn't mean that the instance structure is variable-length (for example, the structure for the list type has fixed-length instances, yet those instances have a meaningful `ob_size`field).
The basic size includes the fields in the instance declared by the macro [`PyObject_HEAD`](structures.xhtml#c.PyObject_HEAD "PyObject_HEAD") or [`PyObject_VAR_HEAD`](structures.xhtml#c.PyObject_VAR_HEAD "PyObject_VAR_HEAD") (whichever is used to declare the instance struct) and this in turn includes the `_ob_prev` and `_ob_next` fields if they are present. This means that the only correct way to get an initializer for the [`tp_basicsize`](#c.PyTypeObject.tp_basicsize "PyTypeObject.tp_basicsize") is to use the `sizeof` operator on the struct used to declare the instance layout. The basic size does not include the GC header size.
These fields are inherited separately by subtypes. If the base type has a non-zero [`tp_itemsize`](#c.PyTypeObject.tp_itemsize "PyTypeObject.tp_itemsize"), it is generally not safe to set [`tp_itemsize`](#c.PyTypeObject.tp_itemsize "PyTypeObject.tp_itemsize") to a different non-zero value in a subtype (though this depends on the implementation of the base type).
A note about alignment: if the variable items require a particular alignment, this should be taken care of by the value of [`tp_basicsize`](#c.PyTypeObject.tp_basicsize "PyTypeObject.tp_basicsize"). Example: suppose a type implements an array of `double`. [`tp_itemsize`](#c.PyTypeObject.tp_itemsize "PyTypeObject.tp_itemsize") is `sizeof(double)`. It is the programmer's responsibility that [`tp_basicsize`](#c.PyTypeObject.tp_basicsize "PyTypeObject.tp_basicsize") is a multiple of `sizeof(double)` (assuming this is the alignment requirement for `double`).
destructor `PyTypeObject.tp_dealloc`A pointer to the instance destructor function. This function must be defined unless the type guarantees that its instances will never be deallocated (as is the case for the singletons `None` and `Ellipsis`).
The destructor function is called by the [`Py_DECREF()`](refcounting.xhtml#c.Py_DECREF "Py_DECREF") and [`Py_XDECREF()`](refcounting.xhtml#c.Py_XDECREF "Py_XDECREF") macros when the new reference count is zero. At this point, the instance is still in existence, but there are no references to it. The destructor function should free all references which the instance owns, free all memory buffers owned by the instance (using the freeing function corresponding to the allocation function used to allocate the buffer), and finally (as its last action) call the type's [`tp_free`](#c.PyTypeObject.tp_free "PyTypeObject.tp_free") function. If the type is not subtypable (doesn't have the [`Py_TPFLAGS_BASETYPE`](#Py_TPFLAGS_BASETYPE "Py_TPFLAGS_BASETYPE") flag bit set), it is permissible to call the object deallocator directly instead of via [`tp_free`](#c.PyTypeObject.tp_free "PyTypeObject.tp_free"). The object deallocator should be the one used to allocate the instance; this is normally [`PyObject_Del()`](allocation.xhtml#c.PyObject_Del "PyObject_Del") if the instance was allocated using [`PyObject_New()`](allocation.xhtml#c.PyObject_New "PyObject_New") or `PyObject_VarNew()`, or [`PyObject_GC_Del()`](gcsupport.xhtml#c.PyObject_GC_Del "PyObject_GC_Del") if the instance was allocated using [`PyObject_GC_New()`](gcsupport.xhtml#c.PyObject_GC_New "PyObject_GC_New") or [`PyObject_GC_NewVar()`](gcsupport.xhtml#c.PyObject_GC_NewVar "PyObject_GC_NewVar").
This field is inherited by subtypes.
printfunc `PyTypeObject.tp_print`Reserved slot, formerly used for print formatting in Python 2.x.
getattrfunc `PyTypeObject.tp_getattr`An optional pointer to the get-attribute-string function.
This field is deprecated. When it is defined, it should point to a function that acts the same as the [`tp_getattro`](#c.PyTypeObject.tp_getattro "PyTypeObject.tp_getattro") function, but taking a C string instead of a Python string object to give the attribute name. The signature is
```
PyObject * tp_getattr(PyObject *o, char *attr_name);
```
This field is inherited by subtypes together with [`tp_getattro`](#c.PyTypeObject.tp_getattro "PyTypeObject.tp_getattro"): a subtype inherits both [`tp_getattr`](#c.PyTypeObject.tp_getattr "PyTypeObject.tp_getattr") and [`tp_getattro`](#c.PyTypeObject.tp_getattro "PyTypeObject.tp_getattro") from its base type when the subtype's [`tp_getattr`](#c.PyTypeObject.tp_getattr "PyTypeObject.tp_getattr") and [`tp_getattro`](#c.PyTypeObject.tp_getattro "PyTypeObject.tp_getattro") are both *NULL*.
setattrfunc `PyTypeObject.tp_setattr`An optional pointer to the function for setting and deleting attributes.
This field is deprecated. When it is defined, it should point to a function that acts the same as the [`tp_setattro`](#c.PyTypeObject.tp_setattro "PyTypeObject.tp_setattro") function, but taking a C string instead of a Python string object to give the attribute name. The signature is
```
PyObject * tp_setattr(PyObject *o, char *attr_name, PyObject *v);
```
The *v* argument is set to *NULL* to delete the attribute. This field is inherited by subtypes together with [`tp_setattro`](#c.PyTypeObject.tp_setattro "PyTypeObject.tp_setattro"): a subtype inherits both [`tp_setattr`](#c.PyTypeObject.tp_setattr "PyTypeObject.tp_setattr") and [`tp_setattro`](#c.PyTypeObject.tp_setattro "PyTypeObject.tp_setattro") from its base type when the subtype's [`tp_setattr`](#c.PyTypeObject.tp_setattr "PyTypeObject.tp_setattr") and [`tp_setattro`](#c.PyTypeObject.tp_setattro "PyTypeObject.tp_setattro") are both *NULL*.
[PyAsyncMethods](#c.PyAsyncMethods "PyAsyncMethods")\* `tp_as_async`Pointer to an additional structure that contains fields relevant only to objects which implement [awaitable](../glossary.xhtml#term-awaitable) and [asynchronous iterator](../glossary.xhtml#term-asynchronous-iterator)protocols at the C-level. See [Async Object Structures](#async-structs) for details.
3\.5 新版功能: Formerly known as `tp_compare` and `tp_reserved`.
reprfunc `PyTypeObject.tp_repr`An optional pointer to a function that implements the built-in function [`repr()`](../library/functions.xhtml#repr "repr").
The signature is the same as for [`PyObject_Repr()`](object.xhtml#c.PyObject_Repr "PyObject_Repr"); it must return a string or a Unicode object. Ideally, this function should return a string that, when passed to [`eval()`](../library/functions.xhtml#eval "eval"), given a suitable environment, returns an object with the same value. If this is not feasible, it should return a string starting with `'<'` and ending with `'>'` from which both the type and the value of the object can be deduced.
When this field is not set, a string of the form `<%s object at %p>` is returned, where `%s` is replaced by the type name, and `%p` by the object's memory address.
This field is inherited by subtypes.
[PyNumberMethods](#c.PyNumberMethods "PyNumberMethods")\* `tp_as_number`Pointer to an additional structure that contains fields relevant only to objects which implement the number protocol. These fields are documented in [Number Object Structures](#number-structs).
The `tp_as_number` field is not inherited, but the contained fields are inherited individually.
[PySequenceMethods](#c.PySequenceMethods "PySequenceMethods")\* `tp_as_sequence`Pointer to an additional structure that contains fields relevant only to objects which implement the sequence protocol. These fields are documented in [Sequence Object Structures](#sequence-structs).
The `tp_as_sequence` field is not inherited, but the contained fields are inherited individually.
[PyMappingMethods](#c.PyMappingMethods "PyMappingMethods")\* `tp_as_mapping`Pointer to an additional structure that contains fields relevant only to objects which implement the mapping protocol. These fields are documented in [Mapping Object Structures](#mapping-structs).
The `tp_as_mapping` field is not inherited, but the contained fields are inherited individually.
hashfunc `PyTypeObject.tp_hash`An optional pointer to a function that implements the built-in function [`hash()`](../library/functions.xhtml#hash "hash").
The signature is the same as for [`PyObject_Hash()`](object.xhtml#c.PyObject_Hash "PyObject_Hash"); it must return a value of the type Py\_hash\_t. The value `-1` should not be returned as a normal return value; when an error occurs during the computation of the hash value, the function should set an exception and return `-1`.
This field can be set explicitly to [`PyObject_HashNotImplemented()`](object.xhtml#c.PyObject_HashNotImplemented "PyObject_HashNotImplemented") to block inheritance of the hash method from a parent type. This is interpreted as the equivalent of `__hash__ = None` at the Python level, causing `isinstance(o, collections.Hashable)` to correctly return `False`. Note that the converse is also true - setting `__hash__ = None` on a class at the Python level will result in the `tp_hash` slot being set to [`PyObject_HashNotImplemented()`](object.xhtml#c.PyObject_HashNotImplemented "PyObject_HashNotImplemented").
When this field is not set, an attempt to take the hash of the object raises [`TypeError`](../library/exceptions.xhtml#TypeError "TypeError").
This field is inherited by subtypes together with [`tp_richcompare`](#c.PyTypeObject.tp_richcompare "PyTypeObject.tp_richcompare"): a subtype inherits both of [`tp_richcompare`](#c.PyTypeObject.tp_richcompare "PyTypeObject.tp_richcompare") and [`tp_hash`](#c.PyTypeObject.tp_hash "PyTypeObject.tp_hash"), when the subtype's [`tp_richcompare`](#c.PyTypeObject.tp_richcompare "PyTypeObject.tp_richcompare") and [`tp_hash`](#c.PyTypeObject.tp_hash "PyTypeObject.tp_hash") are both *NULL*.
ternaryfunc `PyTypeObject.tp_call`An optional pointer to a function that implements calling the object. This should be *NULL* if the object is not callable. The signature is the same as for [`PyObject_Call()`](object.xhtml#c.PyObject_Call "PyObject_Call").
This field is inherited by subtypes.
reprfunc `PyTypeObject.tp_str`An optional pointer to a function that implements the built-in operation [`str()`](../library/stdtypes.xhtml#str "str"). (Note that [`str`](../library/stdtypes.xhtml#str "str") is a type now, and [`str()`](../library/stdtypes.xhtml#str "str") calls the constructor for that type. This constructor calls [`PyObject_Str()`](object.xhtml#c.PyObject_Str "PyObject_Str") to do the actual work, and [`PyObject_Str()`](object.xhtml#c.PyObject_Str "PyObject_Str") will call this handler.)
The signature is the same as for [`PyObject_Str()`](object.xhtml#c.PyObject_Str "PyObject_Str"); it must return a string or a Unicode object. This function should return a "friendly" string representation of the object, as this is the representation that will be used, among other things, by the [`print()`](../library/functions.xhtml#print "print") function.
When this field is not set, [`PyObject_Repr()`](object.xhtml#c.PyObject_Repr "PyObject_Repr") is called to return a string representation.
This field is inherited by subtypes.
getattrofunc `PyTypeObject.tp_getattro`An optional pointer to the get-attribute function.
The signature is the same as for [`PyObject_GetAttr()`](object.xhtml#c.PyObject_GetAttr "PyObject_GetAttr"). It is usually convenient to set this field to [`PyObject_GenericGetAttr()`](object.xhtml#c.PyObject_GenericGetAttr "PyObject_GenericGetAttr"), which implements the normal way of looking for object attributes.
This field is inherited by subtypes together with [`tp_getattr`](#c.PyTypeObject.tp_getattr "PyTypeObject.tp_getattr"): a subtype inherits both [`tp_getattr`](#c.PyTypeObject.tp_getattr "PyTypeObject.tp_getattr") and [`tp_getattro`](#c.PyTypeObject.tp_getattro "PyTypeObject.tp_getattro") from its base type when the subtype's [`tp_getattr`](#c.PyTypeObject.tp_getattr "PyTypeObject.tp_getattr") and [`tp_getattro`](#c.PyTypeObject.tp_getattro "PyTypeObject.tp_getattro") are both *NULL*.
setattrofunc `PyTypeObject.tp_setattro`An optional pointer to the function for setting and deleting attributes.
The signature is the same as for [`PyObject_SetAttr()`](object.xhtml#c.PyObject_SetAttr "PyObject_SetAttr"), but setting *v* to *NULL* to delete an attribute must be supported. It is usually convenient to set this field to [`PyObject_GenericSetAttr()`](object.xhtml#c.PyObject_GenericSetAttr "PyObject_GenericSetAttr"), which implements the normal way of setting object attributes.
This field is inherited by subtypes together with [`tp_setattr`](#c.PyTypeObject.tp_setattr "PyTypeObject.tp_setattr"): a subtype inherits both [`tp_setattr`](#c.PyTypeObject.tp_setattr "PyTypeObject.tp_setattr") and [`tp_setattro`](#c.PyTypeObject.tp_setattro "PyTypeObject.tp_setattro") from its base type when the subtype's [`tp_setattr`](#c.PyTypeObject.tp_setattr "PyTypeObject.tp_setattr") and [`tp_setattro`](#c.PyTypeObject.tp_setattro "PyTypeObject.tp_setattro") are both *NULL*.
[PyBufferProcs](#c.PyBufferProcs "PyBufferProcs")\* `PyTypeObject.tp_as_buffer`Pointer to an additional structure that contains fields relevant only to objects which implement the buffer interface. These fields are documented in [Buffer Object Structures](#buffer-structs).
The [`tp_as_buffer`](#c.PyTypeObject.tp_as_buffer "PyTypeObject.tp_as_buffer") field is not inherited, but the contained fields are inherited individually.
unsigned long `PyTypeObject.tp_flags`This field is a bit mask of various flags. Some flags indicate variant semantics for certain situations; others are used to indicate that certain fields in the type object (or in the extension structures referenced via `tp_as_number`, `tp_as_sequence`, `tp_as_mapping`, and [`tp_as_buffer`](#c.PyTypeObject.tp_as_buffer "PyTypeObject.tp_as_buffer")) that were historically not always present are valid; if such a flag bit is clear, the type fields it guards must not be accessed and must be considered to have a zero or *NULL* value instead.
Inheritance of this field is complicated. Most flag bits are inherited individually, i.e. if the base type has a flag bit set, the subtype inherits this flag bit. The flag bits that pertain to extension structures are strictly inherited if the extension structure is inherited, i.e. the base type's value of the flag bit is copied into the subtype together with a pointer to the extension structure. The [`Py_TPFLAGS_HAVE_GC`](#Py_TPFLAGS_HAVE_GC "Py_TPFLAGS_HAVE_GC") flag bit is inherited together with the [`tp_traverse`](#c.PyTypeObject.tp_traverse "PyTypeObject.tp_traverse") and [`tp_clear`](#c.PyTypeObject.tp_clear "PyTypeObject.tp_clear") fields, i.e. if the [`Py_TPFLAGS_HAVE_GC`](#Py_TPFLAGS_HAVE_GC "Py_TPFLAGS_HAVE_GC") flag bit is clear in the subtype and the [`tp_traverse`](#c.PyTypeObject.tp_traverse "PyTypeObject.tp_traverse") and [`tp_clear`](#c.PyTypeObject.tp_clear "PyTypeObject.tp_clear") fields in the subtype exist and have *NULL* values.
The following bit masks are currently defined; these can be ORed together using the `|` operator to form the value of the [`tp_flags`](#c.PyTypeObject.tp_flags "PyTypeObject.tp_flags") field. The macro [`PyType_HasFeature()`](type.xhtml#c.PyType_HasFeature "PyType_HasFeature") takes a type and a flags value, *tp* and *f*, and checks whether `tp->tp_flags & f` is non-zero.
`Py_TPFLAGS_HEAPTYPE`This bit is set when the type object itself is allocated on the heap. In this case, the `ob_type` field of its instances is considered a reference to the type, and the type object is INCREF'ed when a new instance is created, and DECREF'ed when an instance is destroyed (this does not apply to instances of subtypes; only the type referenced by the instance's ob\_type gets INCREF'ed or DECREF'ed).
`Py_TPFLAGS_BASETYPE`This bit is set when the type can be used as the base type of another type. If this bit is clear, the type cannot be subtyped (similar to a "final" class in Java).
`Py_TPFLAGS_READY`This bit is set when the type object has been fully initialized by [`PyType_Ready()`](type.xhtml#c.PyType_Ready "PyType_Ready").
`Py_TPFLAGS_READYING`This bit is set while [`PyType_Ready()`](type.xhtml#c.PyType_Ready "PyType_Ready") is in the process of initializing the type object.
`Py_TPFLAGS_HAVE_GC`This bit is set when the object supports garbage collection. If this bit is set, instances must be created using [`PyObject_GC_New()`](gcsupport.xhtml#c.PyObject_GC_New "PyObject_GC_New") and destroyed using [`PyObject_GC_Del()`](gcsupport.xhtml#c.PyObject_GC_Del "PyObject_GC_Del"). More information in section [使对象类型支持循环垃圾回收](gcsupport.xhtml#supporting-cycle-detection). This bit also implies that the GC-related fields [`tp_traverse`](#c.PyTypeObject.tp_traverse "PyTypeObject.tp_traverse") and [`tp_clear`](#c.PyTypeObject.tp_clear "PyTypeObject.tp_clear") are present in the type object.
`Py_TPFLAGS_DEFAULT`This is a bitmask of all the bits that pertain to the existence of certain fields in the type object and its extension structures. Currently, it includes the following bits: `Py_TPFLAGS_HAVE_STACKLESS_EXTENSION`, `Py_TPFLAGS_HAVE_VERSION_TAG`.
`Py_TPFLAGS_LONG_SUBCLASS``Py_TPFLAGS_LIST_SUBCLASS``Py_TPFLAGS_TUPLE_SUBCLASS``Py_TPFLAGS_BYTES_SUBCLASS``Py_TPFLAGS_UNICODE_SUBCLASS``Py_TPFLAGS_DICT_SUBCLASS``Py_TPFLAGS_BASE_EXC_SUBCLASS``Py_TPFLAGS_TYPE_SUBCLASS`These flags are used by functions such as [`PyLong_Check()`](long.xhtml#c.PyLong_Check "PyLong_Check") to quickly determine if a type is a subclass of a built-in type; such specific checks are faster than a generic check, like [`PyObject_IsInstance()`](object.xhtml#c.PyObject_IsInstance "PyObject_IsInstance"). Custom types that inherit from built-ins should have their [`tp_flags`](#c.PyTypeObject.tp_flags "PyTypeObject.tp_flags")set appropriately, or the code that interacts with such types will behave differently depending on what kind of check is used.
`Py_TPFLAGS_HAVE_FINALIZE`This bit is set when the [`tp_finalize`](#c.PyTypeObject.tp_finalize "PyTypeObject.tp_finalize") slot is present in the type structure.
3\.4 新版功能.
const char\* `PyTypeObject.tp_doc`An optional pointer to a NUL-terminated C string giving the docstring for this type object. This is exposed as the `__doc__` attribute on the type and instances of the type.
This field is *not* inherited by subtypes.
[traverseproc](gcsupport.xhtml#c.traverseproc "traverseproc")`PyTypeObject.tp_traverse`An optional pointer to a traversal function for the garbage collector. This is only used if the [`Py_TPFLAGS_HAVE_GC`](#Py_TPFLAGS_HAVE_GC "Py_TPFLAGS_HAVE_GC") flag bit is set. More information about Python's garbage collection scheme can be found in section [使对象类型支持循环垃圾回收](gcsupport.xhtml#supporting-cycle-detection).
The [`tp_traverse`](#c.PyTypeObject.tp_traverse "PyTypeObject.tp_traverse") pointer is used by the garbage collector to detect reference cycles. A typical implementation of a [`tp_traverse`](#c.PyTypeObject.tp_traverse "PyTypeObject.tp_traverse") function simply calls [`Py_VISIT()`](gcsupport.xhtml#c.Py_VISIT "Py_VISIT") on each of the instance's members that are Python objects. For example, this is function `local_traverse()` from the [`_thread`](../library/_thread.xhtml#module-_thread "_thread: Low-level threading API.") extension module:
```
static int
local_traverse(localobject *self, visitproc visit, void *arg)
{
Py_VISIT(self->args);
Py_VISIT(self->kw);
Py_VISIT(self->dict);
return 0;
}
```
Note that [`Py_VISIT()`](gcsupport.xhtml#c.Py_VISIT "Py_VISIT") is called only on those members that can participate in reference cycles. Although there is also a `self->key` member, it can only be *NULL* or a Python string and therefore cannot be part of a reference cycle.
On the other hand, even if you know a member can never be part of a cycle, as a debugging aid you may want to visit it anyway just so the [`gc`](../library/gc.xhtml#module-gc "gc: Interface to the cycle-detecting garbage collector.") module's [`get_referents()`](../library/gc.xhtml#gc.get_referents "gc.get_referents") function will include it.
Note that [`Py_VISIT()`](gcsupport.xhtml#c.Py_VISIT "Py_VISIT") requires the *visit* and *arg* parameters to `local_traverse()` to have these specific names; don't name them just anything.
This field is inherited by subtypes together with [`tp_clear`](#c.PyTypeObject.tp_clear "PyTypeObject.tp_clear") and the [`Py_TPFLAGS_HAVE_GC`](#Py_TPFLAGS_HAVE_GC "Py_TPFLAGS_HAVE_GC") flag bit: the flag bit, [`tp_traverse`](#c.PyTypeObject.tp_traverse "PyTypeObject.tp_traverse"), and [`tp_clear`](#c.PyTypeObject.tp_clear "PyTypeObject.tp_clear") are all inherited from the base type if they are all zero in the subtype.
[inquiry](gcsupport.xhtml#c.inquiry "inquiry")`PyTypeObject.tp_clear`An optional pointer to a clear function for the garbage collector. This is only used if the [`Py_TPFLAGS_HAVE_GC`](#Py_TPFLAGS_HAVE_GC "Py_TPFLAGS_HAVE_GC") flag bit is set.
The [`tp_clear`](#c.PyTypeObject.tp_clear "PyTypeObject.tp_clear") member function is used to break reference cycles in cyclic garbage detected by the garbage collector. Taken together, all [`tp_clear`](#c.PyTypeObject.tp_clear "PyTypeObject.tp_clear")functions in the system must combine to break all reference cycles. This is subtle, and if in any doubt supply a [`tp_clear`](#c.PyTypeObject.tp_clear "PyTypeObject.tp_clear") function. For example, the tuple type does not implement a [`tp_clear`](#c.PyTypeObject.tp_clear "PyTypeObject.tp_clear") function, because it's possible to prove that no reference cycle can be composed entirely of tuples. Therefore the [`tp_clear`](#c.PyTypeObject.tp_clear "PyTypeObject.tp_clear") functions of other types must be sufficient to break any cycle containing a tuple. This isn't immediately obvious, and there's rarely a good reason to avoid implementing [`tp_clear`](#c.PyTypeObject.tp_clear "PyTypeObject.tp_clear").
Implementations of [`tp_clear`](#c.PyTypeObject.tp_clear "PyTypeObject.tp_clear") should drop the instance's references to those of its members that may be Python objects, and set its pointers to those members to *NULL*, as in the following example:
```
static int
local_clear(localobject *self)
{
Py_CLEAR(self->key);
Py_CLEAR(self->args);
Py_CLEAR(self->kw);
Py_CLEAR(self->dict);
return 0;
}
```
The [`Py_CLEAR()`](refcounting.xhtml#c.Py_CLEAR "Py_CLEAR") macro should be used, because clearing references is delicate: the reference to the contained object must not be decremented until after the pointer to the contained object is set to *NULL*. This is because decrementing the reference count may cause the contained object to become trash, triggering a chain of reclamation activity that may include invoking arbitrary Python code (due to finalizers, or weakref callbacks, associated with the contained object). If it's possible for such code to reference *self* again, it's important that the pointer to the contained object be *NULL* at that time, so that *self* knows the contained object can no longer be used. The [`Py_CLEAR()`](refcounting.xhtml#c.Py_CLEAR "Py_CLEAR") macro performs the operations in a safe order.
Because the goal of [`tp_clear`](#c.PyTypeObject.tp_clear "PyTypeObject.tp_clear") functions is to break reference cycles, it's not necessary to clear contained objects like Python strings or Python integers, which can't participate in reference cycles. On the other hand, it may be convenient to clear all contained Python objects, and write the type's [`tp_dealloc`](#c.PyTypeObject.tp_dealloc "PyTypeObject.tp_dealloc") function to invoke [`tp_clear`](#c.PyTypeObject.tp_clear "PyTypeObject.tp_clear").
More information about Python's garbage collection scheme can be found in section [使对象类型支持循环垃圾回收](gcsupport.xhtml#supporting-cycle-detection).
This field is inherited by subtypes together with [`tp_traverse`](#c.PyTypeObject.tp_traverse "PyTypeObject.tp_traverse") and the [`Py_TPFLAGS_HAVE_GC`](#Py_TPFLAGS_HAVE_GC "Py_TPFLAGS_HAVE_GC") flag bit: the flag bit, [`tp_traverse`](#c.PyTypeObject.tp_traverse "PyTypeObject.tp_traverse"), and [`tp_clear`](#c.PyTypeObject.tp_clear "PyTypeObject.tp_clear") are all inherited from the base type if they are all zero in the subtype.
richcmpfunc `PyTypeObject.tp_richcompare`An optional pointer to the rich comparison function, whose signature is `PyObject *tp_richcompare(PyObject *a, PyObject *b, int op)`. The first parameter is guaranteed to be an instance of the type that is defined by [`PyTypeObject`](type.xhtml#c.PyTypeObject "PyTypeObject").
The function should return the result of the comparison (usually `Py_True`or `Py_False`). If the comparison is undefined, it must return `Py_NotImplemented`, if another error occurred it must return `NULL` and set an exception condition.
注解
If you want to implement a type for which only a limited set of comparisons makes sense (e.g. `==` and `!=`, but not `<` and friends), directly raise [`TypeError`](../library/exceptions.xhtml#TypeError "TypeError") in the rich comparison function.
This field is inherited by subtypes together with [`tp_hash`](#c.PyTypeObject.tp_hash "PyTypeObject.tp_hash"): a subtype inherits [`tp_richcompare`](#c.PyTypeObject.tp_richcompare "PyTypeObject.tp_richcompare") and [`tp_hash`](#c.PyTypeObject.tp_hash "PyTypeObject.tp_hash") when the subtype's [`tp_richcompare`](#c.PyTypeObject.tp_richcompare "PyTypeObject.tp_richcompare") and [`tp_hash`](#c.PyTypeObject.tp_hash "PyTypeObject.tp_hash") are both *NULL*.
The following constants are defined to be used as the third argument for [`tp_richcompare`](#c.PyTypeObject.tp_richcompare "PyTypeObject.tp_richcompare") and for [`PyObject_RichCompare()`](object.xhtml#c.PyObject_RichCompare "PyObject_RichCompare"):
常数
Comparison
`Py_LT`
`<`
`Py_LE`
`<=`
`Py_EQ`
`==`
`Py_NE`
`!=`
`Py_GT`
`>`
`Py_GE`
`>=`
The following macro is defined to ease writing rich comparison functions:
[PyObject](structures.xhtml#c.PyObject "PyObject") \*`Py_RETURN_RICHCOMPARE`(VAL\_A, VAL\_B, int *op*)Return `Py_True` or `Py_False` from the function, depending on the result of a comparison. VAL\_A and VAL\_B must be orderable by C comparison operators (for example, they may be C ints or floats). The third argument specifies the requested operation, as for [`PyObject_RichCompare()`](object.xhtml#c.PyObject_RichCompare "PyObject_RichCompare").
The return value's reference count is properly incremented.
On error, sets an exception and returns NULL from the function.
3\.7 新版功能.
Py\_ssize\_t `PyTypeObject.tp_weaklistoffset`If the instances of this type are weakly referenceable, this field is greater than zero and contains the offset in the instance structure of the weak reference list head (ignoring the GC header, if present); this offset is used by `PyObject_ClearWeakRefs()` and the `PyWeakref_*()` functions. The instance structure needs to include a field of type [`PyObject*`](structures.xhtml#c.PyObject "PyObject") which is initialized to *NULL*.
Do not confuse this field with [`tp_weaklist`](#c.PyTypeObject.tp_weaklist "PyTypeObject.tp_weaklist"); that is the list head for weak references to the type object itself.
This field is inherited by subtypes, but see the rules listed below. A subtype may override this offset; this means that the subtype uses a different weak reference list head than the base type. Since the list head is always found via [`tp_weaklistoffset`](#c.PyTypeObject.tp_weaklistoffset "PyTypeObject.tp_weaklistoffset"), this should not be a problem.
When a type defined by a class statement has no [`__slots__`](../reference/datamodel.xhtml#object.__slots__ "object.__slots__") declaration, and none of its base types are weakly referenceable, the type is made weakly referenceable by adding a weak reference list head slot to the instance layout and setting the [`tp_weaklistoffset`](#c.PyTypeObject.tp_weaklistoffset "PyTypeObject.tp_weaklistoffset") of that slot's offset.
When a type's `__slots__` declaration contains a slot named `__weakref__`, that slot becomes the weak reference list head for instances of the type, and the slot's offset is stored in the type's [`tp_weaklistoffset`](#c.PyTypeObject.tp_weaklistoffset "PyTypeObject.tp_weaklistoffset").
When a type's `__slots__` declaration does not contain a slot named `__weakref__`, the type inherits its [`tp_weaklistoffset`](#c.PyTypeObject.tp_weaklistoffset "PyTypeObject.tp_weaklistoffset") from its base type.
getiterfunc `PyTypeObject.tp_iter`An optional pointer to a function that returns an iterator for the object. Its presence normally signals that the instances of this type are iterable (although sequences may be iterable without this function).
This function has the same signature as [`PyObject_GetIter()`](object.xhtml#c.PyObject_GetIter "PyObject_GetIter").
This field is inherited by subtypes.
iternextfunc `PyTypeObject.tp_iternext`An optional pointer to a function that returns the next item in an iterator. When the iterator is exhausted, it must return *NULL*; a [`StopIteration`](../library/exceptions.xhtml#StopIteration "StopIteration")exception may or may not be set. When another error occurs, it must return *NULL* too. Its presence signals that the instances of this type are iterators.
Iterator types should also define the [`tp_iter`](#c.PyTypeObject.tp_iter "PyTypeObject.tp_iter") function, and that function should return the iterator instance itself (not a new iterator instance).
This function has the same signature as [`PyIter_Next()`](iter.xhtml#c.PyIter_Next "PyIter_Next").
This field is inherited by subtypes.
struct [PyMethodDef](structures.xhtml#c.PyMethodDef "PyMethodDef")\* `PyTypeObject.tp_methods`An optional pointer to a static *NULL*-terminated array of [`PyMethodDef`](structures.xhtml#c.PyMethodDef "PyMethodDef")structures, declaring regular methods of this type.
For each entry in the array, an entry is added to the type's dictionary (see [`tp_dict`](#c.PyTypeObject.tp_dict "PyTypeObject.tp_dict") below) containing a method descriptor.
This field is not inherited by subtypes (methods are inherited through a different mechanism).
struct [PyMemberDef](structures.xhtml#c.PyMemberDef "PyMemberDef")\* `PyTypeObject.tp_members`An optional pointer to a static *NULL*-terminated array of [`PyMemberDef`](structures.xhtml#c.PyMemberDef "PyMemberDef")structures, declaring regular data members (fields or slots) of instances of this type.
For each entry in the array, an entry is added to the type's dictionary (see [`tp_dict`](#c.PyTypeObject.tp_dict "PyTypeObject.tp_dict") below) containing a member descriptor.
This field is not inherited by subtypes (members are inherited through a different mechanism).
struct [PyGetSetDef](structures.xhtml#c.PyGetSetDef "PyGetSetDef")\* `PyTypeObject.tp_getset`An optional pointer to a static *NULL*-terminated array of [`PyGetSetDef`](structures.xhtml#c.PyGetSetDef "PyGetSetDef")structures, declaring computed attributes of instances of this type.
For each entry in the array, an entry is added to the type's dictionary (see [`tp_dict`](#c.PyTypeObject.tp_dict "PyTypeObject.tp_dict") below) containing a getset descriptor.
This field is not inherited by subtypes (computed attributes are inherited through a different mechanism).
[PyTypeObject](type.xhtml#c.PyTypeObject "PyTypeObject")\* `PyTypeObject.tp_base`An optional pointer to a base type from which type properties are inherited. At this level, only single inheritance is supported; multiple inheritance require dynamically creating a type object by calling the metatype.
This field is not inherited by subtypes (obviously), but it defaults to `&PyBaseObject_Type` (which to Python programmers is known as the type [`object`](../library/functions.xhtml#object "object")).
[PyObject](structures.xhtml#c.PyObject "PyObject")\* `PyTypeObject.tp_dict`The type's dictionary is stored here by [`PyType_Ready()`](type.xhtml#c.PyType_Ready "PyType_Ready").
This field should normally be initialized to *NULL* before PyType\_Ready is called; it may also be initialized to a dictionary containing initial attributes for the type. Once [`PyType_Ready()`](type.xhtml#c.PyType_Ready "PyType_Ready") has initialized the type, extra attributes for the type may be added to this dictionary only if they don't correspond to overloaded operations (like [`__add__()`](../reference/datamodel.xhtml#object.__add__ "object.__add__")).
This field is not inherited by subtypes (though the attributes defined in here are inherited through a different mechanism).
警告
It is not safe to use [`PyDict_SetItem()`](dict.xhtml#c.PyDict_SetItem "PyDict_SetItem") on or otherwise modify [`tp_dict`](#c.PyTypeObject.tp_dict "PyTypeObject.tp_dict") with the dictionary C-API.
descrgetfunc `PyTypeObject.tp_descr_get`An optional pointer to a "descriptor get" function.
The function signature is
```
PyObject * tp_descr_get(PyObject *self, PyObject *obj, PyObject *type);
```
This field is inherited by subtypes.
descrsetfunc `PyTypeObject.tp_descr_set`An optional pointer to a function for setting and deleting a descriptor's value.
The function signature is
```
int tp_descr_set(PyObject *self, PyObject *obj, PyObject *value);
```
The *value* argument is set to *NULL* to delete the value. This field is inherited by subtypes.
Py\_ssize\_t `PyTypeObject.tp_dictoffset`If the instances of this type have a dictionary containing instance variables, this field is non-zero and contains the offset in the instances of the type of the instance variable dictionary; this offset is used by [`PyObject_GenericGetAttr()`](object.xhtml#c.PyObject_GenericGetAttr "PyObject_GenericGetAttr").
Do not confuse this field with [`tp_dict`](#c.PyTypeObject.tp_dict "PyTypeObject.tp_dict"); that is the dictionary for attributes of the type object itself.
If the value of this field is greater than zero, it specifies the offset from the start of the instance structure. If the value is less than zero, it specifies the offset from the *end* of the instance structure. A negative offset is more expensive to use, and should only be used when the instance structure contains a variable-length part. This is used for example to add an instance variable dictionary to subtypes of [`str`](../library/stdtypes.xhtml#str "str") or [`tuple`](../library/stdtypes.xhtml#tuple "tuple"). Note that the [`tp_basicsize`](#c.PyTypeObject.tp_basicsize "PyTypeObject.tp_basicsize") field should account for the dictionary added to the end in that case, even though the dictionary is not included in the basic object layout. On a system with a pointer size of 4 bytes, [`tp_dictoffset`](#c.PyTypeObject.tp_dictoffset "PyTypeObject.tp_dictoffset") should be set to `-4` to indicate that the dictionary is at the very end of the structure.
The real dictionary offset in an instance can be computed from a negative [`tp_dictoffset`](#c.PyTypeObject.tp_dictoffset "PyTypeObject.tp_dictoffset") as follows:
```
dictoffset = tp_basicsize + abs(ob_size)*tp_itemsize + tp_dictoffset
if dictoffset is not aligned on sizeof(void*):
round up to sizeof(void*)
```
where [`tp_basicsize`](#c.PyTypeObject.tp_basicsize "PyTypeObject.tp_basicsize"), [`tp_itemsize`](#c.PyTypeObject.tp_itemsize "PyTypeObject.tp_itemsize") and [`tp_dictoffset`](#c.PyTypeObject.tp_dictoffset "PyTypeObject.tp_dictoffset") are taken from the type object, and `ob_size` is taken from the instance. The absolute value is taken because ints use the sign of `ob_size` to store the sign of the number. (There's never a need to do this calculation yourself; it is done for you by `_PyObject_GetDictPtr()`.)
This field is inherited by subtypes, but see the rules listed below. A subtype may override this offset; this means that the subtype instances store the dictionary at a difference offset than the base type. Since the dictionary is always found via [`tp_dictoffset`](#c.PyTypeObject.tp_dictoffset "PyTypeObject.tp_dictoffset"), this should not be a problem.
When a type defined by a class statement has no [`__slots__`](../reference/datamodel.xhtml#object.__slots__ "object.__slots__") declaration, and none of its base types has an instance variable dictionary, a dictionary slot is added to the instance layout and the [`tp_dictoffset`](#c.PyTypeObject.tp_dictoffset "PyTypeObject.tp_dictoffset") is set to that slot's offset.
When a type defined by a class statement has a `__slots__` declaration, the type inherits its [`tp_dictoffset`](#c.PyTypeObject.tp_dictoffset "PyTypeObject.tp_dictoffset") from its base type.
(Adding a slot named [`__dict__`](../library/stdtypes.xhtml#object.__dict__ "object.__dict__") to the `__slots__` declaration does not have the expected effect, it just causes confusion. Maybe this should be added as a feature just like `__weakref__` though.)
initproc `PyTypeObject.tp_init`An optional pointer to an instance initialization function.
This function corresponds to the [`__init__()`](../reference/datamodel.xhtml#object.__init__ "object.__init__") method of classes. Like [`__init__()`](../reference/datamodel.xhtml#object.__init__ "object.__init__"), it is possible to create an instance without calling [`__init__()`](../reference/datamodel.xhtml#object.__init__ "object.__init__"), and it is possible to reinitialize an instance by calling its [`__init__()`](../reference/datamodel.xhtml#object.__init__ "object.__init__") method again.
The function signature is
```
int tp_init(PyObject *self, PyObject *args, PyObject *kwds)
```
The self argument is the instance to be initialized; the *args* and *kwds*arguments represent positional and keyword arguments of the call to [`__init__()`](../reference/datamodel.xhtml#object.__init__ "object.__init__").
The [`tp_init`](#c.PyTypeObject.tp_init "PyTypeObject.tp_init") function, if not *NULL*, is called when an instance is created normally by calling its type, after the type's [`tp_new`](#c.PyTypeObject.tp_new "PyTypeObject.tp_new") function has returned an instance of the type. If the [`tp_new`](#c.PyTypeObject.tp_new "PyTypeObject.tp_new") function returns an instance of some other type that is not a subtype of the original type, no [`tp_init`](#c.PyTypeObject.tp_init "PyTypeObject.tp_init") function is called; if [`tp_new`](#c.PyTypeObject.tp_new "PyTypeObject.tp_new") returns an instance of a subtype of the original type, the subtype's [`tp_init`](#c.PyTypeObject.tp_init "PyTypeObject.tp_init") is called.
This field is inherited by subtypes.
allocfunc `PyTypeObject.tp_alloc`An optional pointer to an instance allocation function.
The function signature is
```
PyObject *tp_alloc(PyTypeObject *self, Py_ssize_t nitems)
```
The purpose of this function is to separate memory allocation from memory initialization. It should return a pointer to a block of memory of adequate length for the instance, suitably aligned, and initialized to zeros, but with `ob_refcnt` set to `1` and `ob_type` set to the type argument. If the type's [`tp_itemsize`](#c.PyTypeObject.tp_itemsize "PyTypeObject.tp_itemsize") is non-zero, the object's `ob_size` field should be initialized to *nitems* and the length of the allocated memory block should be `tp_basicsize + nitems*tp_itemsize`, rounded up to a multiple of `sizeof(void*)`; otherwise, *nitems* is not used and the length of the block should be [`tp_basicsize`](#c.PyTypeObject.tp_basicsize "PyTypeObject.tp_basicsize").
Do not use this function to do any other instance initialization, not even to allocate additional memory; that should be done by [`tp_new`](#c.PyTypeObject.tp_new "PyTypeObject.tp_new").
This field is inherited by static subtypes, but not by dynamic subtypes (subtypes created by a class statement); in the latter, this field is always set to [`PyType_GenericAlloc()`](type.xhtml#c.PyType_GenericAlloc "PyType_GenericAlloc"), to force a standard heap allocation strategy. That is also the recommended value for statically defined types.
newfunc `PyTypeObject.tp_new`An optional pointer to an instance creation function.
If this function is *NULL* for a particular type, that type cannot be called to create new instances; presumably there is some other way to create instances, like a factory function.
The function signature is
```
PyObject *tp_new(PyTypeObject *subtype, PyObject *args, PyObject *kwds)
```
The subtype argument is the type of the object being created; the *args* and *kwds* arguments represent positional and keyword arguments of the call to the type. Note that subtype doesn't have to equal the type whose [`tp_new`](#c.PyTypeObject.tp_new "PyTypeObject.tp_new")function is called; it may be a subtype of that type (but not an unrelated type).
The [`tp_new`](#c.PyTypeObject.tp_new "PyTypeObject.tp_new") function should call `subtype->tp_alloc(subtype, nitems)`to allocate space for the object, and then do only as much further initialization as is absolutely necessary. Initialization that can safely be ignored or repeated should be placed in the [`tp_init`](#c.PyTypeObject.tp_init "PyTypeObject.tp_init") handler. A good rule of thumb is that for immutable types, all initialization should take place in [`tp_new`](#c.PyTypeObject.tp_new "PyTypeObject.tp_new"), while for mutable types, most initialization should be deferred to [`tp_init`](#c.PyTypeObject.tp_init "PyTypeObject.tp_init").
This field is inherited by subtypes, except it is not inherited by static types whose [`tp_base`](#c.PyTypeObject.tp_base "PyTypeObject.tp_base") is *NULL* or `&PyBaseObject_Type`.
destructor `PyTypeObject.tp_free`An optional pointer to an instance deallocation function. Its signature is `freefunc`:
```
void tp_free(void *)
```
An initializer that is compatible with this signature is [`PyObject_Free()`](memory.xhtml#c.PyObject_Free "PyObject_Free").
This field is inherited by static subtypes, but not by dynamic subtypes (subtypes created by a class statement); in the latter, this field is set to a deallocator suitable to match [`PyType_GenericAlloc()`](type.xhtml#c.PyType_GenericAlloc "PyType_GenericAlloc") and the value of the [`Py_TPFLAGS_HAVE_GC`](#Py_TPFLAGS_HAVE_GC "Py_TPFLAGS_HAVE_GC") flag bit.
[inquiry](gcsupport.xhtml#c.inquiry "inquiry")`PyTypeObject.tp_is_gc`An optional pointer to a function called by the garbage collector.
The garbage collector needs to know whether a particular object is collectible or not. Normally, it is sufficient to look at the object's type's [`tp_flags`](#c.PyTypeObject.tp_flags "PyTypeObject.tp_flags") field, and check the [`Py_TPFLAGS_HAVE_GC`](#Py_TPFLAGS_HAVE_GC "Py_TPFLAGS_HAVE_GC") flag bit. But some types have a mixture of statically and dynamically allocated instances, and the statically allocated instances are not collectible. Such types should define this function; it should return `1` for a collectible instance, and `0` for a non-collectible instance. The signature is
```
int tp_is_gc(PyObject *self)
```
(The only example of this are types themselves. The metatype, [`PyType_Type`](type.xhtml#c.PyType_Type "PyType_Type"), defines this function to distinguish between statically and dynamically allocated types.)
This field is inherited by subtypes.
[PyObject](structures.xhtml#c.PyObject "PyObject")\* `PyTypeObject.tp_bases`Tuple of base types.
This is set for types created by a class statement. It should be *NULL* for statically defined types.
This field is not inherited.
[PyObject](structures.xhtml#c.PyObject "PyObject")\* `PyTypeObject.tp_mro`Tuple containing the expanded set of base types, starting with the type itself and ending with [`object`](../library/functions.xhtml#object "object"), in Method Resolution Order.
This field is not inherited; it is calculated fresh by [`PyType_Ready()`](type.xhtml#c.PyType_Ready "PyType_Ready").
destructor `PyTypeObject.tp_finalize`An optional pointer to an instance finalization function. Its signature is `destructor`:
```
void tp_finalize(PyObject *)
```
If [`tp_finalize`](#c.PyTypeObject.tp_finalize "PyTypeObject.tp_finalize") is set, the interpreter calls it once when finalizing an instance. It is called either from the garbage collector (if the instance is part of an isolated reference cycle) or just before the object is deallocated. Either way, it is guaranteed to be called before attempting to break reference cycles, ensuring that it finds the object in a sane state.
[`tp_finalize`](#c.PyTypeObject.tp_finalize "PyTypeObject.tp_finalize") should not mutate the current exception status; therefore, a recommended way to write a non-trivial finalizer is:
```
static void
local_finalize(PyObject *self)
{
PyObject *error_type, *error_value, *error_traceback;
/* Save the current exception, if any. */
PyErr_Fetch(&error_type, &error_value, &error_traceback);
/* ... */
/* Restore the saved exception. */
PyErr_Restore(error_type, error_value, error_traceback);
}
```
For this field to be taken into account (even through inheritance), you must also set the [`Py_TPFLAGS_HAVE_FINALIZE`](#Py_TPFLAGS_HAVE_FINALIZE "Py_TPFLAGS_HAVE_FINALIZE") flags bit.
This field is inherited by subtypes.
3\.4 新版功能.
参见
"Safe object finalization" ([**PEP 442**](https://www.python.org/dev/peps/pep-0442) \[https://www.python.org/dev/peps/pep-0442\])
[PyObject](structures.xhtml#c.PyObject "PyObject")\* `PyTypeObject.tp_cache`Unused. Not inherited. Internal use only.
[PyObject](structures.xhtml#c.PyObject "PyObject")\* `PyTypeObject.tp_subclasses`List of weak references to subclasses. Not inherited. Internal use only.
[PyObject](structures.xhtml#c.PyObject "PyObject")\* `PyTypeObject.tp_weaklist`Weak reference list head, for weak references to this type object. Not inherited. Internal use only.
The remaining fields are only defined if the feature test macro `COUNT_ALLOCS` is defined, and are for internal use only. They are documented here for completeness. None of these fields are inherited by subtypes.
Py\_ssize\_t `PyTypeObject.tp_allocs`Number of allocations.
Py\_ssize\_t `PyTypeObject.tp_frees`Number of frees.
Py\_ssize\_t `PyTypeObject.tp_maxalloc`Maximum simultaneously allocated objects.
[PyTypeObject](type.xhtml#c.PyTypeObject "PyTypeObject")\* `PyTypeObject.tp_next`Pointer to the next type object with a non-zero [`tp_allocs`](#c.PyTypeObject.tp_allocs "PyTypeObject.tp_allocs") field.
Also, note that, in a garbage collected Python, tp\_dealloc may be called from any Python thread, not just the thread which created the object (if the object becomes part of a refcount cycle, that cycle might be collected by a garbage collection on any thread). This is not a problem for Python API calls, since the thread on which tp\_dealloc is called will own the Global Interpreter Lock (GIL). However, if the object being destroyed in turn destroys objects from some other C or C++ library, care should be taken to ensure that destroying those objects on the thread which called tp\_dealloc will not violate any assumptions of the library.
# Number Object Structures
`PyNumberMethods`This structure holds pointers to the functions which an object uses to implement the number protocol. Each function is used by the function of similar name documented in the [数字协议](number.xhtml#number) section.
Here is the structure definition:
```
typedef struct {
binaryfunc nb_add;
binaryfunc nb_subtract;
binaryfunc nb_multiply;
binaryfunc nb_remainder;
binaryfunc nb_divmod;
ternaryfunc nb_power;
unaryfunc nb_negative;
unaryfunc nb_positive;
unaryfunc nb_absolute;
inquiry nb_bool;
unaryfunc nb_invert;
binaryfunc nb_lshift;
binaryfunc nb_rshift;
binaryfunc nb_and;
binaryfunc nb_xor;
binaryfunc nb_or;
unaryfunc nb_int;
void *nb_reserved;
unaryfunc nb_float;
binaryfunc nb_inplace_add;
binaryfunc nb_inplace_subtract;
binaryfunc nb_inplace_multiply;
binaryfunc nb_inplace_remainder;
ternaryfunc nb_inplace_power;
binaryfunc nb_inplace_lshift;
binaryfunc nb_inplace_rshift;
binaryfunc nb_inplace_and;
binaryfunc nb_inplace_xor;
binaryfunc nb_inplace_or;
binaryfunc nb_floor_divide;
binaryfunc nb_true_divide;
binaryfunc nb_inplace_floor_divide;
binaryfunc nb_inplace_true_divide;
unaryfunc nb_index;
binaryfunc nb_matrix_multiply;
binaryfunc nb_inplace_matrix_multiply;
} PyNumberMethods;
```
注解
Binary and ternary functions must check the type of all their operands, and implement the necessary conversions (at least one of the operands is an instance of the defined type). If the operation is not defined for the given operands, binary and ternary functions must return `Py_NotImplemented`, if another error occurred they must return `NULL`and set an exception.
注解
The `nb_reserved` field should always be `NULL`. It was previously called `nb_long`, and was renamed in Python 3.0.1.
# Mapping Object Structures
`PyMappingMethods`This structure holds pointers to the functions which an object uses to implement the mapping protocol. It has three members:
lenfunc `PyMappingMethods.mp_length`This function is used by [`PyMapping_Size()`](mapping.xhtml#c.PyMapping_Size "PyMapping_Size") and [`PyObject_Size()`](object.xhtml#c.PyObject_Size "PyObject_Size"), and has the same signature. This slot may be set to *NULL* if the object has no defined length.
binaryfunc `PyMappingMethods.mp_subscript`This function is used by [`PyObject_GetItem()`](object.xhtml#c.PyObject_GetItem "PyObject_GetItem") and [`PySequence_GetSlice()`](sequence.xhtml#c.PySequence_GetSlice "PySequence_GetSlice"), and has the same signature as `PyObject_GetItem()`. This slot must be filled for the [`PyMapping_Check()`](mapping.xhtml#c.PyMapping_Check "PyMapping_Check") function to return `1`, it can be *NULL*otherwise.
objobjargproc `PyMappingMethods.mp_ass_subscript`This function is used by [`PyObject_SetItem()`](object.xhtml#c.PyObject_SetItem "PyObject_SetItem"), [`PyObject_DelItem()`](object.xhtml#c.PyObject_DelItem "PyObject_DelItem"), `PyObject_SetSlice()` and `PyObject_DelSlice()`. It has the same signature as `PyObject_SetItem()`, but *v* can also be set to *NULL* to delete an item. If this slot is *NULL*, the object does not support item assignment and deletion.
# Sequence Object Structures
`PySequenceMethods`This structure holds pointers to the functions which an object uses to implement the sequence protocol.
lenfunc `PySequenceMethods.sq_length`This function is used by [`PySequence_Size()`](sequence.xhtml#c.PySequence_Size "PySequence_Size") and [`PyObject_Size()`](object.xhtml#c.PyObject_Size "PyObject_Size"), and has the same signature. It is also used for handling negative indices via the [`sq_item`](#c.PySequenceMethods.sq_item "PySequenceMethods.sq_item")and the [`sq_ass_item`](#c.PySequenceMethods.sq_ass_item "PySequenceMethods.sq_ass_item") slots.
binaryfunc `PySequenceMethods.sq_concat`This function is used by [`PySequence_Concat()`](sequence.xhtml#c.PySequence_Concat "PySequence_Concat") and has the same signature. It is also used by the `+` operator, after trying the numeric addition via the `nb_add` slot.
ssizeargfunc `PySequenceMethods.sq_repeat`This function is used by [`PySequence_Repeat()`](sequence.xhtml#c.PySequence_Repeat "PySequence_Repeat") and has the same signature. It is also used by the `*` operator, after trying numeric multiplication via the `nb_multiply` slot.
ssizeargfunc `PySequenceMethods.sq_item`This function is used by [`PySequence_GetItem()`](sequence.xhtml#c.PySequence_GetItem "PySequence_GetItem") and has the same signature. It is also used by [`PyObject_GetItem()`](object.xhtml#c.PyObject_GetItem "PyObject_GetItem"), after trying the subscription via the [`mp_subscript`](#c.PyMappingMethods.mp_subscript "PyMappingMethods.mp_subscript") slot. This slot must be filled for the [`PySequence_Check()`](sequence.xhtml#c.PySequence_Check "PySequence_Check")function to return `1`, it can be *NULL* otherwise.
Negative indexes are handled as follows: if the `sq_length` slot is filled, it is called and the sequence length is used to compute a positive index which is passed to `sq_item`. If `sq_length` is *NULL*, the index is passed as is to the function.
ssizeobjargproc `PySequenceMethods.sq_ass_item`This function is used by [`PySequence_SetItem()`](sequence.xhtml#c.PySequence_SetItem "PySequence_SetItem") and has the same signature. It is also used by [`PyObject_SetItem()`](object.xhtml#c.PyObject_SetItem "PyObject_SetItem") and [`PyObject_DelItem()`](object.xhtml#c.PyObject_DelItem "PyObject_DelItem"), after trying the item assignment and deletion via the [`mp_ass_subscript`](#c.PyMappingMethods.mp_ass_subscript "PyMappingMethods.mp_ass_subscript") slot. This slot may be left to *NULL* if the object does not support item assignment and deletion.
objobjproc `PySequenceMethods.sq_contains`This function may be used by [`PySequence_Contains()`](sequence.xhtml#c.PySequence_Contains "PySequence_Contains") and has the same signature. This slot may be left to *NULL*, in this case `PySequence_Contains()` simply traverses the sequence until it finds a match.
binaryfunc `PySequenceMethods.sq_inplace_concat`This function is used by [`PySequence_InPlaceConcat()`](sequence.xhtml#c.PySequence_InPlaceConcat "PySequence_InPlaceConcat") and has the same signature. It should modify its first operand, and return it. This slot may be left to *NULL*, in this case `PySequence_InPlaceConcat()`will fall back to [`PySequence_Concat()`](sequence.xhtml#c.PySequence_Concat "PySequence_Concat"). It is also used by the augmented assignment `+=`, after trying numeric in-place addition via the `nb_inplace_add` slot.
ssizeargfunc `PySequenceMethods.sq_inplace_repeat`This function is used by [`PySequence_InPlaceRepeat()`](sequence.xhtml#c.PySequence_InPlaceRepeat "PySequence_InPlaceRepeat") and has the same signature. It should modify its first operand, and return it. This slot may be left to *NULL*, in this case `PySequence_InPlaceRepeat()`will fall back to [`PySequence_Repeat()`](sequence.xhtml#c.PySequence_Repeat "PySequence_Repeat"). It is also used by the augmented assignment `*=`, after trying numeric in-place multiplication via the `nb_inplace_multiply` slot.
# Buffer Object Structures
`PyBufferProcs`This structure holds pointers to the functions required by the [Buffer protocol](buffer.xhtml#bufferobjects). The protocol defines how an exporter object can expose its internal data to consumer objects.
getbufferproc `PyBufferProcs.bf_getbuffer`The signature of this function is:
```
int (PyObject *exporter, Py_buffer *view, int flags);
```
Handle a request to *exporter* to fill in *view* as specified by *flags*. Except for point (3), an implementation of this function MUST take these steps:
1. Check if the request can be met. If not, raise `PyExc_BufferError`, set `view->obj` to *NULL* and return `-1`.
2. Fill in the requested fields.
3. Increment an internal counter for the number of exports.
4. Set `view->obj` to *exporter* and increment `view->obj`.
5. Return `0`.
If *exporter* is part of a chain or tree of buffer providers, two main schemes can be used:
- Re-export: Each member of the tree acts as the exporting object and sets `view->obj` to a new reference to itself.
- Redirect: The buffer request is redirected to the root object of the tree. Here, `view->obj` will be a new reference to the root object.
The individual fields of *view* are described in section [Buffer structure](buffer.xhtml#buffer-structure), the rules how an exporter must react to specific requests are in section [Buffer request types](buffer.xhtml#buffer-request-types).
All memory pointed to in the [`Py_buffer`](buffer.xhtml#c.Py_buffer "Py_buffer") structure belongs to the exporter and must remain valid until there are no consumers left. [`format`](buffer.xhtml#c.Py_buffer.format "Py_buffer.format"), [`shape`](buffer.xhtml#c.Py_buffer.shape "Py_buffer.shape"), [`strides`](buffer.xhtml#c.Py_buffer.strides "Py_buffer.strides"), [`suboffsets`](buffer.xhtml#c.Py_buffer.suboffsets "Py_buffer.suboffsets")and [`internal`](buffer.xhtml#c.Py_buffer.internal "Py_buffer.internal")are read-only for the consumer.
[`PyBuffer_FillInfo()`](buffer.xhtml#c.PyBuffer_FillInfo "PyBuffer_FillInfo") provides an easy way of exposing a simple bytes buffer while dealing correctly with all request types.
[`PyObject_GetBuffer()`](buffer.xhtml#c.PyObject_GetBuffer "PyObject_GetBuffer") is the interface for the consumer that wraps this function.
releasebufferproc `PyBufferProcs.bf_releasebuffer`The signature of this function is:
```
void (PyObject *exporter, Py_buffer *view);
```
Handle a request to release the resources of the buffer. If no resources need to be released, [`PyBufferProcs.bf_releasebuffer`](#c.PyBufferProcs.bf_releasebuffer "PyBufferProcs.bf_releasebuffer") may be *NULL*. Otherwise, a standard implementation of this function will take these optional steps:
1. Decrement an internal counter for the number of exports.
2. If the counter is `0`, free all memory associated with *view*.
The exporter MUST use the [`internal`](buffer.xhtml#c.Py_buffer.internal "Py_buffer.internal") field to keep track of buffer-specific resources. This field is guaranteed to remain constant, while a consumer MAY pass a copy of the original buffer as the *view* argument.
This function MUST NOT decrement `view->obj`, since that is done automatically in [`PyBuffer_Release()`](buffer.xhtml#c.PyBuffer_Release "PyBuffer_Release") (this scheme is useful for breaking reference cycles).
[`PyBuffer_Release()`](buffer.xhtml#c.PyBuffer_Release "PyBuffer_Release") is the interface for the consumer that wraps this function.
# Async Object Structures
3\.5 新版功能.
`PyAsyncMethods`This structure holds pointers to the functions required to implement [awaitable](../glossary.xhtml#term-awaitable) and [asynchronous iterator](../glossary.xhtml#term-asynchronous-iterator) objects.
Here is the structure definition:
```
typedef struct {
unaryfunc am_await;
unaryfunc am_aiter;
unaryfunc am_anext;
} PyAsyncMethods;
```
unaryfunc `PyAsyncMethods.am_await`The signature of this function is:
```
PyObject *am_await(PyObject *self)
```
The returned object must be an iterator, i.e. [`PyIter_Check()`](iter.xhtml#c.PyIter_Check "PyIter_Check") must return `1` for it.
This slot may be set to *NULL* if an object is not an [awaitable](../glossary.xhtml#term-awaitable).
unaryfunc `PyAsyncMethods.am_aiter`The signature of this function is:
```
PyObject *am_aiter(PyObject *self)
```
Must return an [awaitable](../glossary.xhtml#term-awaitable) object. See [`__anext__()`](../reference/datamodel.xhtml#object.__anext__ "object.__anext__") for details.
This slot may be set to *NULL* if an object does not implement asynchronous iteration protocol.
unaryfunc `PyAsyncMethods.am_anext`The signature of this function is:
```
PyObject *am_anext(PyObject *self)
```
Must return an [awaitable](../glossary.xhtml#term-awaitable) object. See [`__anext__()`](../reference/datamodel.xhtml#object.__anext__ "object.__anext__") for details. This slot may be set to *NULL*.
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- 文件通配符
- 命令行参数
- 错误输出重定向和程序终止
- 字符串模式匹配
- 数学
- 互联网访问
- 日期和时间
- 数据压缩
- 性能测量
- 质量控制
- 自带电池
- 标准库简介 —— 第二部分
- 格式化输出
- 模板
- 使用二进制数据记录格式
- 多线程
- 日志
- 弱引用
- 用于操作列表的工具
- 十进制浮点运算
- 虚拟环境和包
- 概述
- 创建虚拟环境
- 使用pip管理包
- 接下来?
- 交互式编辑和编辑历史
- Tab 补全和编辑历史
- 默认交互式解释器的替代品
- 浮点算术:争议和限制
- 表示性错误
- 附录
- 交互模式
- 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