270 lines
9.1 KiB
ReStructuredText
270 lines
9.1 KiB
ReStructuredText
.. highlight:: c
|
|
|
|
.. _typeobjects:
|
|
|
|
Type Objects
|
|
------------
|
|
|
|
.. index:: object: type
|
|
|
|
|
|
.. c:type:: PyTypeObject
|
|
|
|
The C structure of the objects used to describe built-in types.
|
|
|
|
|
|
.. c:var:: PyObject* 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.
|
|
|
|
|
|
.. 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.
|
|
|
|
|
|
.. 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 limited API.
|
|
|
|
.. versionadded:: 3.2
|
|
|
|
.. versionchanged:: 3.4
|
|
The return type is now ``unsigned long`` rather than ``long``.
|
|
|
|
|
|
.. 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_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 :const:`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:`~class.__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.
|
|
|
|
.. 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 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.
|
|
|
|
.. 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
|
|
|
|
|
|
Creating Heap-Allocated Types
|
|
.............................
|
|
|
|
The following functions and structs are used to create
|
|
:ref:`heap types <heap-types>`.
|
|
|
|
.. c:function:: PyObject* PyType_FromModuleAndSpec(PyObject *module, PyType_Spec *spec, PyObject *bases)
|
|
|
|
Creates and returns a heap type object from the *spec*
|
|
(:const:`Py_TPFLAGS_HEAPTYPE`).
|
|
|
|
If *bases* is a tuple, the created heap type contains all types contained
|
|
in it as base types.
|
|
|
|
If *bases* 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
|
|
retreived 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.
|
|
|
|
.. versionadded:: 3.9
|
|
|
|
.. versionchanged:: 3.10
|
|
|
|
The function now accepts NULL ``tp_doc`` slot.
|
|
|
|
.. c:function:: PyObject* PyType_FromSpecWithBases(PyType_Spec *spec, PyObject *bases)
|
|
|
|
Equivalent to ``PyType_FromModuleAndSpec(NULL, spec, bases)``.
|
|
|
|
.. versionadded:: 3.3
|
|
|
|
.. c:function:: PyObject* PyType_FromSpec(PyType_Spec *spec)
|
|
|
|
Equivalent to ``PyType_FromSpecWithBases(spec, NULL)``.
|
|
|
|
.. c:type:: PyType_Spec
|
|
|
|
Structure defining a type's behavior.
|
|
|
|
.. c:member:: const char* PyType_Spec.name
|
|
|
|
Name of the type, used to set :c:member:`PyTypeObject.tp_name`.
|
|
|
|
.. c:member:: int PyType_Spec.basicsize
|
|
.. c:member:: int PyType_Spec.itemsize
|
|
|
|
Size of the instance in bytes, used to set
|
|
:c:member:`PyTypeObject.tp_basicsize` and
|
|
:c:member:`PyTypeObject.tp_itemsize`.
|
|
|
|
.. c:member:: int PyType_Spec.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 *PyType_Spec.slots
|
|
|
|
Array of :c:type:`PyType_Slot` structures.
|
|
Terminated by the special slot value ``{0, NULL}``.
|
|
|
|
.. c:type:: PyType_Slot
|
|
|
|
Structure defining optional functionality of a type, containing a slot ID
|
|
and a value pointer.
|
|
|
|
.. c:member:: int PyType_Slot.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`
|
|
|
|
The following fields cannot be set at all using :c:type:`PyType_Spec` and
|
|
:c:type:`PyType_Slot`:
|
|
|
|
* :c:member:`~PyTypeObject.tp_dict`
|
|
* :c:member:`~PyTypeObject.tp_mro`
|
|
* :c:member:`~PyTypeObject.tp_cache`
|
|
* :c:member:`~PyTypeObject.tp_subclasses`
|
|
* :c:member:`~PyTypeObject.tp_weaklist`
|
|
* :c:member:`~PyTypeObject.tp_vectorcall`
|
|
* :c:member:`~PyTypeObject.tp_weaklistoffset`
|
|
(see :ref:`PyMemberDef <pymemberdef-offsets>`)
|
|
* :c:member:`~PyTypeObject.tp_dictoffset`
|
|
(see :ref:`PyMemberDef <pymemberdef-offsets>`)
|
|
* :c:member:`~PyTypeObject.tp_vectorcall_offset`
|
|
(see :ref:`PyMemberDef <pymemberdef-offsets>`)
|
|
|
|
The following fields cannot be set using :c:type:`PyType_Spec` and
|
|
:c:type:`PyType_Slot` under the limited API:
|
|
|
|
* :c:member:`~PyBufferProcs.bf_getbuffer`
|
|
* :c:member:`~PyBufferProcs.bf_releasebuffer`
|
|
|
|
Setting :c:data:`Py_tp_bases` may be problematic on some platforms.
|
|
To avoid issues, use the *bases* argument of
|
|
:py:func:`PyType_FromSpecWithBases` instead.
|
|
|
|
.. versionchanged:: 3.9
|
|
|
|
Slots in :c:type:`PyBufferProcs` in may be set in the unlimited API.
|
|
|
|
.. c:member:: void *PyType_Slot.pfunc
|
|
|
|
The desired value of the slot. In most cases, this is a pointer
|
|
to a function.
|
|
|
|
Slots other than ``Py_tp_doc`` may not be ``NULL``.
|