mirror of
https://github.com/python/cpython.git
synced 2025-11-03 23:21:29 +00:00
ad0f618ab3
* Update documentation for tp_basicsize & tp_itemsize - Add alignment requirement - Mention that ob_size is unreliable if you don't control it - Add some links for context - basicsize should include the base type in generaly not just PyObject This adds a “by-the-way” link to `PyObject_New`, which shouldn't be used for GC types. In order to be comfortable linking to it, I also add a link to `PyObject_GC_New` from its docs. And the same for `*Var` variants, while I'm here. * Strongly suggest Py_SIZE & Py_SET_SIZE
624 lines
22 KiB
ReStructuredText
624 lines
22 KiB
ReStructuredText
.. highlight:: c
|
|
|
|
.. _typeobjects:
|
|
|
|
Type Objects
|
|
------------
|
|
|
|
.. index:: pair: object; type
|
|
|
|
|
|
.. c:type:: PyTypeObject
|
|
|
|
The C structure of the objects used to describe built-in types.
|
|
|
|
|
|
.. c:var:: PyTypeObject PyType_Type
|
|
|
|
This is the type object for type objects; it is the same object as
|
|
:class:`type` in the Python layer.
|
|
|
|
|
|
.. c:function:: int PyType_Check(PyObject *o)
|
|
|
|
Return non-zero if the object *o* is a type object, including instances of
|
|
types derived from the standard type object. Return 0 in all other cases.
|
|
This function always succeeds.
|
|
|
|
|
|
.. c:function:: int PyType_CheckExact(PyObject *o)
|
|
|
|
Return non-zero if the object *o* is a type object, but not a subtype of
|
|
the standard type object. Return 0 in all other cases. This function
|
|
always succeeds.
|
|
|
|
|
|
.. c:function:: unsigned int PyType_ClearCache()
|
|
|
|
Clear the internal lookup cache. Return the current version tag.
|
|
|
|
.. c:function:: unsigned long PyType_GetFlags(PyTypeObject* type)
|
|
|
|
Return the :c:member:`~PyTypeObject.tp_flags` member of *type*. This function is primarily
|
|
meant for use with ``Py_LIMITED_API``; the individual flag bits are
|
|
guaranteed to be stable across Python releases, but access to
|
|
:c:member:`~PyTypeObject.tp_flags` itself is not part of the :ref:`limited API <limited-c-api>`.
|
|
|
|
.. versionadded:: 3.2
|
|
|
|
.. versionchanged:: 3.4
|
|
The return type is now ``unsigned long`` rather than ``long``.
|
|
|
|
|
|
.. c:function:: PyObject* PyType_GetDict(PyTypeObject* type)
|
|
|
|
Return the type object's internal namespace, which is otherwise only
|
|
exposed via a read-only proxy (:attr:`cls.__dict__ <type.__dict__>`).
|
|
This is a
|
|
replacement for accessing :c:member:`~PyTypeObject.tp_dict` directly.
|
|
The returned dictionary must be treated as read-only.
|
|
|
|
This function is meant for specific embedding and language-binding cases,
|
|
where direct access to the dict is necessary and indirect access
|
|
(e.g. via the proxy or :c:func:`PyObject_GetAttr`) isn't adequate.
|
|
|
|
Extension modules should continue to use ``tp_dict``,
|
|
directly or indirectly, when setting up their own types.
|
|
|
|
.. versionadded:: 3.12
|
|
|
|
|
|
.. c:function:: void PyType_Modified(PyTypeObject *type)
|
|
|
|
Invalidate the internal lookup cache for the type and all of its
|
|
subtypes. This function must be called after any manual
|
|
modification of the attributes or base classes of the type.
|
|
|
|
|
|
.. c:function:: int PyType_AddWatcher(PyType_WatchCallback callback)
|
|
|
|
Register *callback* as a type watcher. Return a non-negative integer ID
|
|
which must be passed to future calls to :c:func:`PyType_Watch`. In case of
|
|
error (e.g. no more watcher IDs available), return ``-1`` and set an
|
|
exception.
|
|
|
|
.. versionadded:: 3.12
|
|
|
|
|
|
.. c:function:: int PyType_ClearWatcher(int watcher_id)
|
|
|
|
Clear watcher identified by *watcher_id* (previously returned from
|
|
:c:func:`PyType_AddWatcher`). Return ``0`` on success, ``-1`` on error (e.g.
|
|
if *watcher_id* was never registered.)
|
|
|
|
An extension should never call ``PyType_ClearWatcher`` with a *watcher_id*
|
|
that was not returned to it by a previous call to
|
|
:c:func:`PyType_AddWatcher`.
|
|
|
|
.. versionadded:: 3.12
|
|
|
|
|
|
.. c:function:: int PyType_Watch(int watcher_id, PyObject *type)
|
|
|
|
Mark *type* as watched. The callback granted *watcher_id* by
|
|
:c:func:`PyType_AddWatcher` will be called whenever
|
|
:c:func:`PyType_Modified` reports a change to *type*. (The callback may be
|
|
called only once for a series of consecutive modifications to *type*, if
|
|
:c:func:`!_PyType_Lookup` is not called on *type* between the modifications;
|
|
this is an implementation detail and subject to change.)
|
|
|
|
An extension should never call ``PyType_Watch`` with a *watcher_id* that was
|
|
not returned to it by a previous call to :c:func:`PyType_AddWatcher`.
|
|
|
|
.. versionadded:: 3.12
|
|
|
|
|
|
.. c:type:: int (*PyType_WatchCallback)(PyObject *type)
|
|
|
|
Type of a type-watcher callback function.
|
|
|
|
The callback must not modify *type* or cause :c:func:`PyType_Modified` to be
|
|
called on *type* or any type in its MRO; violating this rule could cause
|
|
infinite recursion.
|
|
|
|
.. versionadded:: 3.12
|
|
|
|
|
|
.. c:function:: int PyType_HasFeature(PyTypeObject *o, int feature)
|
|
|
|
Return non-zero if the type object *o* sets the feature *feature*.
|
|
Type features are denoted by single bit flags.
|
|
|
|
|
|
.. c:function:: int PyType_IS_GC(PyTypeObject *o)
|
|
|
|
Return true if the type object includes support for the cycle detector; this
|
|
tests the type flag :c:macro:`Py_TPFLAGS_HAVE_GC`.
|
|
|
|
|
|
.. c:function:: int PyType_IsSubtype(PyTypeObject *a, PyTypeObject *b)
|
|
|
|
Return true if *a* is a subtype of *b*.
|
|
|
|
This function only checks for actual subtypes, which means that
|
|
:meth:`~type.__subclasscheck__` is not called on *b*. Call
|
|
:c:func:`PyObject_IsSubclass` to do the same check that :func:`issubclass`
|
|
would do.
|
|
|
|
|
|
.. c:function:: PyObject* PyType_GenericAlloc(PyTypeObject *type, Py_ssize_t nitems)
|
|
|
|
Generic handler for the :c:member:`~PyTypeObject.tp_alloc` slot of a type object. Use
|
|
Python's default memory allocation mechanism to allocate a new instance and
|
|
initialize all its contents to ``NULL``.
|
|
|
|
.. c:function:: PyObject* PyType_GenericNew(PyTypeObject *type, PyObject *args, PyObject *kwds)
|
|
|
|
Generic handler for the :c:member:`~PyTypeObject.tp_new` slot of a type object. Create a
|
|
new instance using the type's :c:member:`~PyTypeObject.tp_alloc` slot.
|
|
|
|
.. c:function:: int PyType_Ready(PyTypeObject *type)
|
|
|
|
Finalize a type object. This should be called on all type objects to finish
|
|
their initialization. This function is responsible for adding inherited slots
|
|
from a type's base class. Return ``0`` on success, or return ``-1`` and sets an
|
|
exception on error.
|
|
|
|
.. note::
|
|
If some of the base classes implements the GC protocol and the provided
|
|
type does not include the :c:macro:`Py_TPFLAGS_HAVE_GC` in its flags, then
|
|
the GC protocol will be automatically implemented from its parents. On
|
|
the contrary, if the type being created does include
|
|
:c:macro:`Py_TPFLAGS_HAVE_GC` in its flags then it **must** implement the
|
|
GC protocol itself by at least implementing the
|
|
:c:member:`~PyTypeObject.tp_traverse` handle.
|
|
|
|
.. c:function:: PyObject* PyType_GetName(PyTypeObject *type)
|
|
|
|
Return the type's name. Equivalent to getting the type's
|
|
:attr:`~type.__name__` attribute.
|
|
|
|
.. versionadded:: 3.11
|
|
|
|
.. c:function:: PyObject* PyType_GetQualName(PyTypeObject *type)
|
|
|
|
Return the type's qualified name. Equivalent to getting the
|
|
type's :attr:`~type.__qualname__` attribute.
|
|
|
|
.. versionadded:: 3.11
|
|
|
|
.. c:function:: PyObject* PyType_GetFullyQualifiedName(PyTypeObject *type)
|
|
|
|
Return the type's fully qualified name. Equivalent to
|
|
``f"{type.__module__}.{type.__qualname__}"``, or :attr:`type.__qualname__`
|
|
if :attr:`type.__module__` is not a string or is equal to ``"builtins"``.
|
|
|
|
.. versionadded:: 3.13
|
|
|
|
.. c:function:: PyObject* PyType_GetModuleName(PyTypeObject *type)
|
|
|
|
Return the type's module name. Equivalent to getting the
|
|
:attr:`type.__module__` attribute.
|
|
|
|
.. versionadded:: 3.13
|
|
|
|
.. c:function:: void* PyType_GetSlot(PyTypeObject *type, int slot)
|
|
|
|
Return the function pointer stored in the given slot. If the
|
|
result is ``NULL``, this indicates that either the slot is ``NULL``,
|
|
or that the function was called with invalid parameters.
|
|
Callers will typically cast the result pointer into the appropriate
|
|
function type.
|
|
|
|
See :c:member:`PyType_Slot.slot` for possible values of the *slot* argument.
|
|
|
|
.. versionadded:: 3.4
|
|
|
|
.. versionchanged:: 3.10
|
|
:c:func:`PyType_GetSlot` can now accept all types.
|
|
Previously, it was limited to :ref:`heap types <heap-types>`.
|
|
|
|
.. c:function:: PyObject* PyType_GetModule(PyTypeObject *type)
|
|
|
|
Return the module object associated with the given type when the type was
|
|
created using :c:func:`PyType_FromModuleAndSpec`.
|
|
|
|
If no module is associated with the given type, sets :py:class:`TypeError`
|
|
and returns ``NULL``.
|
|
|
|
This function is usually used to get the module in which a method is defined.
|
|
Note that in such a method, ``PyType_GetModule(Py_TYPE(self))``
|
|
may not return the intended result.
|
|
``Py_TYPE(self)`` may be a *subclass* of the intended class, and subclasses
|
|
are not necessarily defined in the same module as their superclass.
|
|
See :c:type:`PyCMethod` to get the class that defines the method.
|
|
See :c:func:`PyType_GetModuleByDef` for cases when :c:type:`!PyCMethod` cannot
|
|
be used.
|
|
|
|
.. versionadded:: 3.9
|
|
|
|
.. c:function:: void* PyType_GetModuleState(PyTypeObject *type)
|
|
|
|
Return the state of the module object associated with the given type.
|
|
This is a shortcut for calling :c:func:`PyModule_GetState()` on the result
|
|
of :c:func:`PyType_GetModule`.
|
|
|
|
If no module is associated with the given type, sets :py:class:`TypeError`
|
|
and returns ``NULL``.
|
|
|
|
If the *type* has an associated module but its state is ``NULL``,
|
|
returns ``NULL`` without setting an exception.
|
|
|
|
.. versionadded:: 3.9
|
|
|
|
.. c:function:: PyObject* PyType_GetModuleByDef(PyTypeObject *type, struct PyModuleDef *def)
|
|
|
|
Find the first superclass whose module was created from
|
|
the given :c:type:`PyModuleDef` *def*, and return that module.
|
|
|
|
If no module is found, raises a :py:class:`TypeError` and returns ``NULL``.
|
|
|
|
This function is intended to be used together with
|
|
:c:func:`PyModule_GetState()` to get module state from slot methods (such as
|
|
:c:member:`~PyTypeObject.tp_init` or :c:member:`~PyNumberMethods.nb_add`)
|
|
and other places where a method's defining class cannot be passed using the
|
|
:c:type:`PyCMethod` calling convention.
|
|
|
|
.. versionadded:: 3.11
|
|
|
|
.. c:function:: int PyType_GetBaseByToken(PyTypeObject *type, void *token, PyTypeObject **result)
|
|
|
|
Find the first superclass in *type*'s :term:`method resolution order` whose
|
|
:c:macro:`Py_tp_token` token is equal to the given one.
|
|
|
|
* If found, set *\*result* to a new :term:`strong reference`
|
|
to it and return ``1``.
|
|
* If not found, set *\*result* to ``NULL`` and return ``0``.
|
|
* On error, set *\*result* to ``NULL`` and return ``-1`` with an
|
|
exception set.
|
|
|
|
The *result* argument may be ``NULL``, in which case *\*result* is not set.
|
|
Use this if you need only the return value.
|
|
|
|
The *token* argument may not be ``NULL``.
|
|
|
|
.. versionadded:: 3.14
|
|
|
|
.. c:function:: int PyUnstable_Type_AssignVersionTag(PyTypeObject *type)
|
|
|
|
Attempt to assign a version tag to the given type.
|
|
|
|
Returns 1 if the type already had a valid version tag or a new one was
|
|
assigned, or 0 if a new tag could not be assigned.
|
|
|
|
.. versionadded:: 3.12
|
|
|
|
|
|
Creating Heap-Allocated Types
|
|
.............................
|
|
|
|
The following functions and structs are used to create
|
|
:ref:`heap types <heap-types>`.
|
|
|
|
.. c:function:: PyObject* PyType_FromMetaclass(PyTypeObject *metaclass, PyObject *module, PyType_Spec *spec, PyObject *bases)
|
|
|
|
Create and return a :ref:`heap type <heap-types>` from the *spec*
|
|
(see :c:macro:`Py_TPFLAGS_HEAPTYPE`).
|
|
|
|
The metaclass *metaclass* is used to construct the resulting type object.
|
|
When *metaclass* is ``NULL``, the metaclass is derived from *bases*
|
|
(or *Py_tp_base[s]* slots if *bases* is ``NULL``, see below).
|
|
|
|
Metaclasses that override :c:member:`~PyTypeObject.tp_new` are not
|
|
supported, except if ``tp_new`` is ``NULL``.
|
|
(For backwards compatibility, other ``PyType_From*`` functions allow
|
|
such metaclasses. They ignore ``tp_new``, which may result in incomplete
|
|
initialization. This is deprecated and in Python 3.14+ such metaclasses will
|
|
not be supported.)
|
|
|
|
The *bases* argument can be used to specify base classes; it can either
|
|
be only one class or a tuple of classes.
|
|
If *bases* is ``NULL``, the *Py_tp_bases* slot is used instead.
|
|
If that also is ``NULL``, the *Py_tp_base* slot is used instead.
|
|
If that also is ``NULL``, the new type derives from :class:`object`.
|
|
|
|
The *module* argument can be used to record the module in which the new
|
|
class is defined. It must be a module object or ``NULL``.
|
|
If not ``NULL``, the module is associated with the new type and can later be
|
|
retrieved with :c:func:`PyType_GetModule`.
|
|
The associated module is not inherited by subclasses; it must be specified
|
|
for each class individually.
|
|
|
|
This function calls :c:func:`PyType_Ready` on the new type.
|
|
|
|
Note that this function does *not* fully match the behavior of
|
|
calling :py:class:`type() <type>` or using the :keyword:`class` statement.
|
|
With user-provided base types or metaclasses, prefer
|
|
:ref:`calling <capi-call>` :py:class:`type` (or the metaclass)
|
|
over ``PyType_From*`` functions.
|
|
Specifically:
|
|
|
|
* :py:meth:`~object.__new__` is not called on the new class
|
|
(and it must be set to ``type.__new__``).
|
|
* :py:meth:`~object.__init__` is not called on the new class.
|
|
* :py:meth:`~object.__init_subclass__` is not called on any bases.
|
|
* :py:meth:`~object.__set_name__` is not called on new descriptors.
|
|
|
|
.. versionadded:: 3.12
|
|
|
|
.. c:function:: PyObject* PyType_FromModuleAndSpec(PyObject *module, PyType_Spec *spec, PyObject *bases)
|
|
|
|
Equivalent to ``PyType_FromMetaclass(NULL, module, spec, bases)``.
|
|
|
|
.. versionadded:: 3.9
|
|
|
|
.. versionchanged:: 3.10
|
|
|
|
The function now accepts a single class as the *bases* argument and
|
|
``NULL`` as the ``tp_doc`` slot.
|
|
|
|
.. versionchanged:: 3.12
|
|
|
|
The function now finds and uses a metaclass corresponding to the provided
|
|
base classes. Previously, only :class:`type` instances were returned.
|
|
|
|
The :c:member:`~PyTypeObject.tp_new` of the metaclass is *ignored*.
|
|
which may result in incomplete initialization.
|
|
Creating classes whose metaclass overrides
|
|
:c:member:`~PyTypeObject.tp_new` is deprecated.
|
|
|
|
.. versionchanged:: 3.14
|
|
|
|
Creating classes whose metaclass overrides
|
|
:c:member:`~PyTypeObject.tp_new` is no longer allowed.
|
|
|
|
.. c:function:: PyObject* PyType_FromSpecWithBases(PyType_Spec *spec, PyObject *bases)
|
|
|
|
Equivalent to ``PyType_FromMetaclass(NULL, NULL, spec, bases)``.
|
|
|
|
.. versionadded:: 3.3
|
|
|
|
.. versionchanged:: 3.12
|
|
|
|
The function now finds and uses a metaclass corresponding to the provided
|
|
base classes. Previously, only :class:`type` instances were returned.
|
|
|
|
The :c:member:`~PyTypeObject.tp_new` of the metaclass is *ignored*.
|
|
which may result in incomplete initialization.
|
|
Creating classes whose metaclass overrides
|
|
:c:member:`~PyTypeObject.tp_new` is deprecated.
|
|
|
|
.. versionchanged:: 3.14
|
|
|
|
Creating classes whose metaclass overrides
|
|
:c:member:`~PyTypeObject.tp_new` is no longer allowed.
|
|
|
|
.. c:function:: PyObject* PyType_FromSpec(PyType_Spec *spec)
|
|
|
|
Equivalent to ``PyType_FromMetaclass(NULL, NULL, spec, NULL)``.
|
|
|
|
.. versionchanged:: 3.12
|
|
|
|
The function now finds and uses a metaclass corresponding to the
|
|
base classes provided in *Py_tp_base[s]* slots.
|
|
Previously, only :class:`type` instances were returned.
|
|
|
|
The :c:member:`~PyTypeObject.tp_new` of the metaclass is *ignored*.
|
|
which may result in incomplete initialization.
|
|
Creating classes whose metaclass overrides
|
|
:c:member:`~PyTypeObject.tp_new` is deprecated.
|
|
|
|
.. versionchanged:: 3.14
|
|
|
|
Creating classes whose metaclass overrides
|
|
:c:member:`~PyTypeObject.tp_new` is no longer allowed.
|
|
|
|
.. c:function:: int PyType_Freeze(PyTypeObject *type)
|
|
|
|
Make a type immutable: set the :c:macro:`Py_TPFLAGS_IMMUTABLETYPE` flag.
|
|
|
|
All base classes of *type* must be immutable.
|
|
|
|
On success, return ``0``.
|
|
On error, set an exception and return ``-1``.
|
|
|
|
The type must not be used before it's made immutable. For example, type
|
|
instances must not be created before the type is made immutable.
|
|
|
|
.. versionadded:: 3.14
|
|
|
|
.. raw:: html
|
|
|
|
<!-- Keep old URL fragments working (see gh-97908) -->
|
|
<span id='c.PyType_Spec.PyType_Spec.name'></span>
|
|
<span id='c.PyType_Spec.PyType_Spec.basicsize'></span>
|
|
<span id='c.PyType_Spec.PyType_Spec.itemsize'></span>
|
|
<span id='c.PyType_Spec.PyType_Spec.flags'></span>
|
|
<span id='c.PyType_Spec.PyType_Spec.slots'></span>
|
|
|
|
.. c:type:: PyType_Spec
|
|
|
|
Structure defining a type's behavior.
|
|
|
|
.. c:member:: const char* name
|
|
|
|
Name of the type, used to set :c:member:`PyTypeObject.tp_name`.
|
|
|
|
.. c:member:: int basicsize
|
|
|
|
If positive, specifies the size of the instance in bytes.
|
|
It is used to set :c:member:`PyTypeObject.tp_basicsize`.
|
|
|
|
If zero, specifies that :c:member:`~PyTypeObject.tp_basicsize`
|
|
should be inherited.
|
|
|
|
If negative, the absolute value specifies how much space instances of the
|
|
class need *in addition* to the superclass.
|
|
Use :c:func:`PyObject_GetTypeData` to get a pointer to subclass-specific
|
|
memory reserved this way.
|
|
For negative :c:member:`!basicsize`, Python will insert padding when
|
|
needed to meet :c:member:`~PyTypeObject.tp_basicsize`'s alignment
|
|
requirements.
|
|
|
|
.. versionchanged:: 3.12
|
|
|
|
Previously, this field could not be negative.
|
|
|
|
.. c:member:: int itemsize
|
|
|
|
Size of one element of a variable-size type, in bytes.
|
|
Used to set :c:member:`PyTypeObject.tp_itemsize`.
|
|
See ``tp_itemsize`` documentation for caveats.
|
|
|
|
If zero, :c:member:`~PyTypeObject.tp_itemsize` is inherited.
|
|
Extending arbitrary variable-sized classes is dangerous,
|
|
since some types use a fixed offset for variable-sized memory,
|
|
which can then overlap fixed-sized memory used by a subclass.
|
|
To help prevent mistakes, inheriting ``itemsize`` is only possible
|
|
in the following situations:
|
|
|
|
- The base is not variable-sized (its
|
|
:c:member:`~PyTypeObject.tp_itemsize`).
|
|
- The requested :c:member:`PyType_Spec.basicsize` is positive,
|
|
suggesting that the memory layout of the base class is known.
|
|
- The requested :c:member:`PyType_Spec.basicsize` is zero,
|
|
suggesting that the subclass does not access the instance's memory
|
|
directly.
|
|
- With the :c:macro:`Py_TPFLAGS_ITEMS_AT_END` flag.
|
|
|
|
.. c:member:: unsigned int flags
|
|
|
|
Type flags, used to set :c:member:`PyTypeObject.tp_flags`.
|
|
|
|
If the ``Py_TPFLAGS_HEAPTYPE`` flag is not set,
|
|
:c:func:`PyType_FromSpecWithBases` sets it automatically.
|
|
|
|
.. c:member:: PyType_Slot *slots
|
|
|
|
Array of :c:type:`PyType_Slot` structures.
|
|
Terminated by the special slot value ``{0, NULL}``.
|
|
|
|
Each slot ID should be specified at most once.
|
|
|
|
.. raw:: html
|
|
|
|
<!-- Keep old URL fragments working (see gh-97908) -->
|
|
<span id='c.PyType_Slot.PyType_Slot.slot'></span>
|
|
<span id='c.PyType_Slot.PyType_Slot.pfunc'></span>
|
|
|
|
.. c:type:: PyType_Slot
|
|
|
|
Structure defining optional functionality of a type, containing a slot ID
|
|
and a value pointer.
|
|
|
|
.. c:member:: int slot
|
|
|
|
A slot ID.
|
|
|
|
Slot IDs are named like the field names of the structures
|
|
:c:type:`PyTypeObject`, :c:type:`PyNumberMethods`,
|
|
:c:type:`PySequenceMethods`, :c:type:`PyMappingMethods` and
|
|
:c:type:`PyAsyncMethods` with an added ``Py_`` prefix.
|
|
For example, use:
|
|
|
|
* ``Py_tp_dealloc`` to set :c:member:`PyTypeObject.tp_dealloc`
|
|
* ``Py_nb_add`` to set :c:member:`PyNumberMethods.nb_add`
|
|
* ``Py_sq_length`` to set :c:member:`PySequenceMethods.sq_length`
|
|
|
|
An additional slot is supported that does not correspond to a
|
|
:c:type:`!PyTypeObject` struct field:
|
|
|
|
* :c:data:`Py_tp_token`
|
|
|
|
The following “offset” fields cannot be set using :c:type:`PyType_Slot`:
|
|
|
|
* :c:member:`~PyTypeObject.tp_weaklistoffset`
|
|
(use :c:macro:`Py_TPFLAGS_MANAGED_WEAKREF` instead if possible)
|
|
* :c:member:`~PyTypeObject.tp_dictoffset`
|
|
(use :c:macro:`Py_TPFLAGS_MANAGED_DICT` instead if possible)
|
|
* :c:member:`~PyTypeObject.tp_vectorcall_offset`
|
|
(use ``"__vectorcalloffset__"`` in
|
|
:ref:`PyMemberDef <pymemberdef-offsets>`)
|
|
|
|
If it is not possible to switch to a ``MANAGED`` flag (for example,
|
|
for vectorcall or to support Python older than 3.12), specify the
|
|
offset in :c:member:`Py_tp_members <PyTypeObject.tp_members>`.
|
|
See :ref:`PyMemberDef documentation <pymemberdef-offsets>`
|
|
for details.
|
|
|
|
The following internal fields cannot be set at all when creating a heap
|
|
type:
|
|
|
|
* :c:member:`~PyTypeObject.tp_dict`,
|
|
:c:member:`~PyTypeObject.tp_mro`,
|
|
:c:member:`~PyTypeObject.tp_cache`,
|
|
:c:member:`~PyTypeObject.tp_subclasses`, and
|
|
:c:member:`~PyTypeObject.tp_weaklist`.
|
|
|
|
Setting :c:data:`Py_tp_bases` or :c:data:`Py_tp_base` may be
|
|
problematic on some platforms.
|
|
To avoid issues, use the *bases* argument of
|
|
:c:func:`PyType_FromSpecWithBases` instead.
|
|
|
|
.. versionchanged:: 3.9
|
|
Slots in :c:type:`PyBufferProcs` may be set in the unlimited API.
|
|
|
|
.. versionchanged:: 3.11
|
|
:c:member:`~PyBufferProcs.bf_getbuffer` and
|
|
:c:member:`~PyBufferProcs.bf_releasebuffer` are now available
|
|
under the :ref:`limited API <limited-c-api>`.
|
|
|
|
.. versionchanged:: 3.14
|
|
The field :c:member:`~PyTypeObject.tp_vectorcall` can now set
|
|
using ``Py_tp_vectorcall``. See the field's documentation
|
|
for details.
|
|
|
|
.. c:member:: void *pfunc
|
|
|
|
The desired value of the slot. In most cases, this is a pointer
|
|
to a function.
|
|
|
|
*pfunc* values may not be ``NULL``, except for the following slots:
|
|
|
|
* ``Py_tp_doc``
|
|
* :c:data:`Py_tp_token` (for clarity, prefer :c:data:`Py_TP_USE_SPEC`
|
|
rather than ``NULL``)
|
|
|
|
.. c:macro:: Py_tp_token
|
|
|
|
A :c:member:`~PyType_Slot.slot` that records a static memory layout ID
|
|
for a class.
|
|
|
|
If the :c:type:`PyType_Spec` of the class is statically
|
|
allocated, the token can be set to the spec using the special value
|
|
:c:data:`Py_TP_USE_SPEC`:
|
|
|
|
.. code-block:: c
|
|
|
|
static PyType_Slot foo_slots[] = {
|
|
{Py_tp_token, Py_TP_USE_SPEC},
|
|
|
|
It can also be set to an arbitrary pointer, but you must ensure that:
|
|
|
|
* The pointer outlives the class, so it's not reused for something else
|
|
while the class exists.
|
|
* It "belongs" to the extension module where the class lives, so it will not
|
|
clash with other extensions.
|
|
|
|
Use :c:func:`PyType_GetBaseByToken` to check if a class's superclass has
|
|
a given token -- that is, check whether the memory layout is compatible.
|
|
|
|
To get the token for a given class (without considering superclasses),
|
|
use :c:func:`PyType_GetSlot` with ``Py_tp_token``.
|
|
|
|
.. versionadded:: 3.14
|
|
|
|
.. c:namespace:: NULL
|
|
|
|
.. c:macro:: Py_TP_USE_SPEC
|
|
|
|
Used as a value with :c:data:`Py_tp_token` to set the token to the
|
|
class's :c:type:`PyType_Spec`.
|
|
Expands to ``NULL``.
|
|
|
|
.. versionadded:: 3.14
|