Загальні структури об’єктів¶
Існує велика кількість структур, які використовуються для визначення типів об’єктів для Python. У цьому розділі описано ці структури та як вони використовуються.
Базові типи об’єктів і макроси¶
All Python objects ultimately share a small number of fields at the beginning
of the object’s representation in memory. These are represented by the
PyObject
and PyVarObject
types, which are defined, in turn,
by the expansions of some macros also used, whether directly or indirectly, in
the definition of all other Python objects. Additional macros can be found
under reference counting.
-
type PyObject¶
- Part of the Limited API. (Only some members are part of the stable ABI.)
All object types are extensions of this type. This is a type which contains the information Python needs to treat a pointer to an object as an object. In a normal «release» build, it contains only the object’s reference count and a pointer to the corresponding type object. Nothing is actually declared to be a
PyObject
, but every pointer to a Python object can be cast to a PyObject*. Access to the members must be done by using the macrosPy_REFCNT
andPy_TYPE
.
-
type PyVarObject¶
- Part of the Limited API. (Only some members are part of the stable ABI.)
This is an extension of
PyObject
that adds theob_size
field. This is only used for objects that have some notion of length. This type does not often appear in the Python/C API. Access to the members must be done by using the macrosPy_REFCNT
,Py_TYPE
, andPy_SIZE
.
-
PyObject_HEAD¶
Це макрос, який використовується під час оголошення нових типів, які представляють об’єкти без змінної довжини. Макрос PyObject_HEAD розширюється до:
PyObject ob_base;
Перегляньте документацію
PyObject
вище.
-
PyObject_VAR_HEAD¶
Це макрос, який використовується під час оголошення нових типів, які представляють об’єкти з довжиною, що змінюється від екземпляра до екземпляра. Макрос PyObject_VAR_HEAD розширюється до:
PyVarObject ob_base;
Перегляньте документацію
PyVarObject
вище.
-
int Py_Is(PyObject *x, PyObject *y)¶
- Part of the Stable ABI since version 3.10.
Перевірте, чи є об’єкт x об’єктом y, так само як «x є y» в Python.
Added in version 3.10.
-
int Py_IsNone(PyObject *x)¶
- Part of the Stable ABI since version 3.10.
Перевірте, чи є об’єкт єдиним елементом
None
, так само якx is None
у Python.Added in version 3.10.
-
int Py_IsTrue(PyObject *x)¶
- Part of the Stable ABI since version 3.10.
Перевірте, чи є об’єкт єдиним елементом
True
, так само, якx is True
у Python.Added in version 3.10.
-
int Py_IsFalse(PyObject *x)¶
- Part of the Stable ABI since version 3.10.
Перевірте, чи є об’єкт синглетом
False
, так само, якx is False
у Python.Added in version 3.10.
-
PyTypeObject *Py_TYPE(PyObject *o)¶
- Return value: Borrowed reference.
Отримайте тип об’єкта Python o.
Повертає borrowed reference.
Use the
Py_SET_TYPE()
function to set an object type.
-
int Py_IS_TYPE(PyObject *o, PyTypeObject *type)¶
Повертає ненульове значення, якщо тип об’єкта o є type. Інакше поверніть нуль. Еквівалент:
Py_TYPE(o) == type
.Added in version 3.9.
-
void Py_SET_TYPE(PyObject *o, PyTypeObject *type)¶
Встановіть тип об’єкта o на type.
Added in version 3.9.
-
Py_ssize_t Py_SIZE(PyVarObject *o)¶
Отримайте розмір об’єкта Python o.
Use the
Py_SET_SIZE()
function to set an object size.Змінено в версії 3.11:
Py_SIZE()
is changed to an inline static function. The parameter type is no longer const PyVarObject*.
-
void Py_SET_SIZE(PyVarObject *o, Py_ssize_t size)¶
Встановіть розмір об’єкта o на size.
Added in version 3.9.
-
PyObject_HEAD_INIT(type)¶
Це макрос, який розширюється до значень ініціалізації для нового типу
PyObject
. Цей макрос розширюється до:_PyObject_EXTRA_INIT 1, type,
-
PyVarObject_HEAD_INIT(type, size)¶
This is a macro which expands to initialization values for a new
PyVarObject
type, including theob_size
field. This macro expands to:_PyObject_EXTRA_INIT 1, type, size,
Реалізація функцій і методів¶
-
type PyCFunction¶
- Part of the Stable ABI.
Type of the functions used to implement most Python callables in C. Functions of this type take two PyObject* parameters and return one such value. If the return value is
NULL
, an exception shall have been set. If notNULL
, the return value is interpreted as the return value of the function as exposed in Python. The function must return a new reference.Сигнатура функції:
PyObject *PyCFunction(PyObject *self, PyObject *args);
-
type PyCFunctionWithKeywords¶
- Part of the Stable ABI.
Type of the functions used to implement Python callables in C with signature METH_VARARGS | METH_KEYWORDS. The function signature is:
PyObject *PyCFunctionWithKeywords(PyObject *self, PyObject *args, PyObject *kwargs);
-
type PyCFunctionFast¶
- Part of the Stable ABI since version 3.13.
Type of the functions used to implement Python callables in C with signature
METH_FASTCALL
. The function signature is:PyObject *PyCFunctionFast(PyObject *self, PyObject *const *args, Py_ssize_t nargs);
-
type PyCFunctionFastWithKeywords¶
- Part of the Stable ABI since version 3.13.
Type of the functions used to implement Python callables in C with signature METH_FASTCALL | METH_KEYWORDS. The function signature is:
PyObject *PyCFunctionFastWithKeywords(PyObject *self, PyObject *const *args, Py_ssize_t nargs, PyObject *kwnames);
-
type PyCMethod¶
Type of the functions used to implement Python callables in C with signature METH_METHOD | METH_FASTCALL | METH_KEYWORDS. The function signature is:
PyObject *PyCMethod(PyObject *self, PyTypeObject *defining_class, PyObject *const *args, Py_ssize_t nargs, PyObject *kwnames)
Added in version 3.9.
-
type PyMethodDef¶
- Part of the Stable ABI (including all members).
Структура, що використовується для опису методу типу розширення. Ця структура має чотири поля:
-
const char *ml_name¶
Name of the method.
-
PyCFunction ml_meth¶
Pointer to the C implementation.
-
int ml_flags¶
Flags bits indicating how the call should be constructed.
-
const char *ml_doc¶
Points to the contents of the docstring.
-
const char *ml_name¶
The ml_meth
is a C function pointer.
The functions may be of different
types, but they always return PyObject*. If the function is not of
the PyCFunction
, the compiler will require a cast in the method table.
Even though PyCFunction
defines the first parameter as
PyObject*, it is common that the method implementation uses the
specific C type of the self object.
The ml_flags
field is a bitfield which can include
the following flags.
The individual flags indicate either a calling convention or a binding
convention.
Існують такі умови виклику:
-
METH_VARARGS¶
This is the typical calling convention, where the methods have the type
PyCFunction
. The function expects two PyObject* values. The first one is the self object for methods; for module functions, it is the module object. The second parameter (often called args) is a tuple object representing all arguments. This parameter is typically processed usingPyArg_ParseTuple()
orPyArg_UnpackTuple()
.
-
METH_KEYWORDS¶
Can only be used in certain combinations with other flags: METH_VARARGS | METH_KEYWORDS, METH_FASTCALL | METH_KEYWORDS and METH_METHOD | METH_FASTCALL | METH_KEYWORDS.
- METH_VARARGS | METH_KEYWORDS
Методи з цими прапорцями мають бути типу
PyCFunctionWithKeywords
. Функція очікує три параметри: self, args, kwargs, де kwargs є словником усіх аргументів ключового слова або, можливо,NULL
, якщо аргументів ключового слова немає. Параметри зазвичай обробляються за допомогоюPyArg_ParseTupleAndKeywords()
.
-
METH_FASTCALL¶
Fast calling convention supporting only positional arguments. The methods have the type
PyCFunctionFast
. The first parameter is self, the second parameter is a C array of PyObject* values indicating the arguments and the third parameter is the number of arguments (the length of the array).Added in version 3.7.
Змінено в версії 3.10:
METH_FASTCALL
is now part of the stable ABI.
- METH_FASTCALL | METH_KEYWORDS
Extension of
METH_FASTCALL
supporting also keyword arguments, with methods of typePyCFunctionFastWithKeywords
. Keyword arguments are passed the same way as in the vectorcall protocol: there is an additional fourth PyObject* parameter which is a tuple representing the names of the keyword arguments (which are guaranteed to be strings) or possiblyNULL
if there are no keywords. The values of the keyword arguments are stored in the args array, after the positional arguments.Added in version 3.7.
-
METH_METHOD¶
Can only be used in the combination with other flags: METH_METHOD | METH_FASTCALL | METH_KEYWORDS.
- METH_METHOD | METH_FASTCALL | METH_KEYWORDS
Extension of METH_FASTCALL | METH_KEYWORDS supporting the defining class, that is, the class that contains the method in question. The defining class might be a superclass of
Py_TYPE(self)
.Метод має мати тип
PyCMethod
, такий самий, як і дляMETH_FASTCALL | METH_KEYWORDS
з аргументомdefining_class
, доданим післяself
.Added in version 3.9.
-
METH_NOARGS¶
Methods without parameters don’t need to check whether arguments are given if they are listed with the
METH_NOARGS
flag. They need to be of typePyCFunction
. The first parameter is typically named self and will hold a reference to the module or object instance. In all cases the second parameter will beNULL
.The function must have 2 parameters. Since the second parameter is unused,
Py_UNUSED
can be used to prevent a compiler warning.
-
METH_O¶
Methods with a single object argument can be listed with the
METH_O
flag, instead of invokingPyArg_ParseTuple()
with a"O"
argument. They have the typePyCFunction
, with the self parameter, and a PyObject* parameter representing the single argument.
Ці дві константи не використовуються для вказівки умов виклику, а для прив’язки під час використання з методами класів. Їх не можна використовувати для функцій, визначених для модулів. Щонайбільше один із цих прапорів може бути встановлений для будь-якого методу.
-
METH_CLASS¶
Методу буде передано об’єкт типу як перший параметр, а не екземпляр типу. Це використовується для створення методів класу, подібних до того, що створюється під час використання вбудованої функції
classmethod()
.
-
METH_STATIC¶
Методу буде передано
NULL
як перший параметр, а не екземпляр типу. Це використовується для створення статичних методів, подібних до того, що створюється під час використання вбудованої функціїstaticmethod()
.
Ще одна константа контролює, чи завантажується метод замість іншого визначення з таким же ім’ям методу.
-
METH_COEXIST¶
The method will be loaded in place of existing definitions. Without METH_COEXIST, the default is to skip repeated definitions. Since slot wrappers are loaded before the method table, the existence of a sq_contains slot, for example, would generate a wrapped method named
__contains__()
and preclude the loading of a corresponding PyCFunction with the same name. With the flag defined, the PyCFunction will be loaded in place of the wrapper object and will co-exist with the slot. This is helpful because calls to PyCFunctions are optimized more than wrapper object calls.
-
PyObject *PyCMethod_New(PyMethodDef *ml, PyObject *self, PyObject *module, PyTypeObject *cls)¶
- Return value: New reference. Part of the Stable ABI since version 3.9.
Turn ml into a Python callable object. The caller must ensure that ml outlives the callable. Typically, ml is defined as a static variable.
The self parameter will be passed as the self argument to the C function in
ml->ml_meth
when invoked. self can beNULL
.The callable object’s
__module__
attribute can be set from the given module argument. module should be a Python string, which will be used as name of the module the function is defined in. If unavailable, it can be set toNone
orNULL
.Дивись також
The cls parameter will be passed as the defining_class argument to the C function. Must be set if
METH_METHOD
is set onml->ml_flags
.Added in version 3.9.
-
PyObject *PyCFunction_NewEx(PyMethodDef *ml, PyObject *self, PyObject *module)¶
- Return value: New reference. Part of the Stable ABI.
Equivalent to
PyCMethod_New(ml, self, module, NULL)
.
-
PyObject *PyCFunction_New(PyMethodDef *ml, PyObject *self)¶
- Return value: New reference. Part of the Stable ABI since version 3.4.
Equivalent to
PyCMethod_New(ml, self, NULL, NULL)
.
Доступ до атрибутів типів розширень¶
-
type PyMemberDef¶
- Part of the Stable ABI (including all members).
Structure which describes an attribute of a type which corresponds to a C struct member. When defining a class, put a NULL-terminated array of these structures in the
tp_members
slot.Its fields are, in order:
-
const char *name¶
Name of the member. A NULL value marks the end of a
PyMemberDef[]
array.The string should be static, no copy is made of it.
-
int type¶
The type of the member in the C struct. See Member types for the possible values.
-
Py_ssize_t offset¶
The offset in bytes that the member is located on the type’s object struct.
-
int flags¶
Zero or more of the Member flags, combined using bitwise OR.
-
const char *doc¶
The docstring, or NULL. The string should be static, no copy is made of it. Typically, it is defined using
PyDoc_STR
.
By default (when
flags
is0
), members allow both read and write access. Use thePy_READONLY
flag for read-only access. Certain types, likePy_T_STRING
, implyPy_READONLY
. OnlyPy_T_OBJECT_EX
(and legacyT_OBJECT
) members can be deleted.For heap-allocated types (created using
PyType_FromSpec()
or similar),PyMemberDef
may contain a definition for the special member"__vectorcalloffset__"
, corresponding totp_vectorcall_offset
in type objects. These must be defined withPy_T_PYSSIZET
andPy_READONLY
, for example:static PyMemberDef spam_type_members[] = { {"__vectorcalloffset__", Py_T_PYSSIZET, offsetof(Spam_object, vectorcall), Py_READONLY}, {NULL} /* Sentinel */ };
(You may need to
#include <stddef.h>
foroffsetof()
.)The legacy offsets
tp_dictoffset
andtp_weaklistoffset
can be defined similarly using"__dictoffset__"
and"__weaklistoffset__"
members, but extensions are strongly encouraged to usePy_TPFLAGS_MANAGED_DICT
andPy_TPFLAGS_MANAGED_WEAKREF
instead.Змінено в версії 3.12:
PyMemberDef
is always available. Previously, it required including"structmember.h"
. -
const char *name¶
-
PyObject *PyMember_GetOne(const char *obj_addr, struct PyMemberDef *m)¶
- Part of the Stable ABI.
Отримати атрибут, що належить об’єкту за адресою obj_addr. Атрибут описується
PyMemberDef
m. ПовертаєNULL
у разі помилки.Змінено в версії 3.12:
PyMember_GetOne
is always available. Previously, it required including"structmember.h"
.
-
int PyMember_SetOne(char *obj_addr, struct PyMemberDef *m, PyObject *o)¶
- Part of the Stable ABI.
Установіть атрибут, що належить об’єкту за адресою obj_addr, на об’єкт o. Атрибут, який потрібно встановити, описується
PyMemberDef
m. Повертає0
у разі успіху та від’ємне значення у випадку невдачі.Змінено в версії 3.12:
PyMember_SetOne
is always available. Previously, it required including"structmember.h"
.
Member flags¶
The following flags can be used with PyMemberDef.flags
:
-
Py_READONLY¶
Not writable.
-
Py_AUDIT_READ¶
Emit an
object.__getattr__
audit event before reading.
-
Py_RELATIVE_OFFSET¶
Indicates that the
offset
of thisPyMemberDef
entry indicates an offset from the subclass-specific data, rather than fromPyObject
.Can only be used as part of
Py_tp_members
slot
when creating a class using negativebasicsize
. It is mandatory in that case.This flag is only used in
PyType_Slot
. When settingtp_members
during class creation, Python clears it and setsPyMemberDef.offset
to the offset from thePyObject
struct.
Змінено в версії 3.10: The RESTRICTED
, READ_RESTRICTED
and
WRITE_RESTRICTED
macros available with
#include "structmember.h"
are deprecated.
READ_RESTRICTED
and RESTRICTED
are equivalent to
Py_AUDIT_READ
; WRITE_RESTRICTED
does nothing.
Змінено в версії 3.12: The READONLY
macro was renamed to Py_READONLY
.
The PY_AUDIT_READ
macro was renamed with the Py_
prefix.
The new names are now always available.
Previously, these required #include "structmember.h"
.
The header is still available and it provides the old names.
Member types¶
PyMemberDef.type
can be one of the following macros corresponding
to various C types.
When the member is accessed in Python, it will be converted to the
equivalent Python type.
When it is set from Python, it will be converted back to the C type.
If that is not possible, an exception such as TypeError
or
ValueError
is raised.
Unless marked (D), attributes defined this way cannot be deleted
using e.g. del
or delattr()
.
Назва макросу |
тип С |
Тип Python |
---|---|---|
|
char |
|
|
short |
|
|
int |
|
|
long |
|
|
long long |
|
|
unsigned char |
|
|
unsigned int |
|
|
unsigned short |
|
|
unsigned long |
|
|
unsigned long long |
|
|
||
|
float |
|
|
double |
|
|
char (written as 0 or 1) |
|
|
const char* (*) |
|
|
const char[] (*) |
|
|
char (0-127) |
|
|
|
(*): Zero-terminated, UTF8-encoded C string. With
Py_T_STRING
the C representation is a pointer; withPy_T_STRING_INPLACE
the string is stored directly in the structure.(**): String of length 1. Only ASCII is accepted.
(RO): Implies
Py_READONLY
.(D): Can be deleted, in which case the pointer is set to
NULL
. Reading aNULL
pointer raisesAttributeError
.
Added in version 3.12: In previous versions, the macros were only available with
#include "structmember.h"
and were named without the Py_
prefix
(e.g. as T_INT
).
The header is still available and contains the old names, along with
the following deprecated types:
-
T_OBJECT¶
Like
Py_T_OBJECT_EX
, butNULL
is converted toNone
. This results in surprising behavior in Python: deleting the attribute effectively sets it toNone
.
-
T_NONE¶
Always
None
. Must be used withPy_READONLY
.
Defining Getters and Setters¶
-
type PyGetSetDef¶
- Part of the Stable ABI (including all members).
Структура для визначення доступу типу властивості. Дивіться також опис слота
PyTypeObject.tp_getset
.-
const char *name¶
назва атрибута
-
setter set¶
Optional C function to set or delete the attribute. If
NULL
, the attribute is read-only.
-
const char *doc¶
додатковий рядок документації
-
void *closure¶
Optional user data pointer, providing additional data for getter and setter.
-
const char *name¶
-
typedef PyObject *(*getter)(PyObject*, void*)¶
- Part of the Stable ABI.
The
get
function takes one PyObject* parameter (the instance) and a user data pointer (the associatedclosure
):Він повинен повертати нове посилання в разі успіху або
NULL
із встановленим винятком у випадку невдачі.
-
typedef int (*setter)(PyObject*, PyObject*, void*)¶
- Part of the Stable ABI.
set
functions take two PyObject* parameters (the instance and the value to be set) and a user data pointer (the associatedclosure
):У випадку, якщо атрибут потрібно видалити, другим параметром є
NULL
. Має повертати0
у разі успіху або-1
із встановленим винятком у випадку невдачі.