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bpo-44392: Add Py_GenericAlias to C API docs (GH-26724)

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Also fix stable ABI type definitions
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Ken Jin 2021-06-16 22:12:25 +08:00 committed by GitHub
parent ab030d6f9d
commit 6773c3eaa7
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6 changed files with 53 additions and 3 deletions
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1
Doc/c-api/concrete.rst
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@ -115,3 +115,4 @@ Other Objects
coro.rst
contextvars.rst
datetime.rst
typehints.rst

47
Doc/c-api/typehints.rst Normal file
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@ -0,0 +1,47 @@
.. highlight:: c
.. _typehintobjects:
Objects for Type Hinting
------------------------
Various built-in types for type hinting are provided. Currently,
two types exist -- :ref:`GenericAlias <types-genericalias>` and
:ref:`Union <types-union>`. Only ``GenericAlias`` is exposed to C.
.. c:function:: PyObject* Py_GenericAlias(PyObject *origin, PyObject *args)
Create a :ref:`GenericAlias <types-genericalias>` object.
Equivalent to calling the Python class
:class:`types.GenericAlias`. The *origin* and *args* arguments set the
``GenericAlias``\ 's ``__origin__`` and ``__args__`` attributes respectively.
*origin* should be a :c:type:`PyTypeObject*`, and *args* can be a
:c:type:`PyTupleObject*` or any ``PyObject*``. If *args* passed is
not a tuple, a 1-tuple is automatically constructed and ``__args__`` is set
to ``(args,)``.
Minimal checking is done for the arguments, so the function will succeed even
if *origin* is not a type.
The ``GenericAlias``\ 's ``__parameters__`` attribute is constructed lazily
from ``__args__``. On failure, an exception is raised and ``NULL`` is
returned.
Here's an example of how to make an extension type generic::
...
static PyMethodDef my_obj_methods[] = {
// Other methods.
...
{"__class_getitem__", (PyCFunction)Py_GenericAlias, METH_O|METH_CLASS, "See PEP 585"}
...
}
.. seealso:: The data model method :meth:`__class_getitem__`.
.. versionadded:: 3.9
.. c:var:: PyTypeObject Py_GenericAliasType
The C type of the object returned by :c:func:`Py_GenericAlias`. Equivalent to
:class:`types.GenericAlias` in Python.
.. versionadded:: 3.9

2
Doc/data/stable_abi.dat
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@ -785,7 +785,7 @@ var,Py_FileSystemDefaultEncoding,3.2,
function,Py_Finalize,3.2,
function,Py_FinalizeEx,3.6,
function,Py_GenericAlias,3.9,
function,Py_GenericAliasType,3.9,
var,Py_GenericAliasType,3.9,
function,Py_GetBuildInfo,3.2,
function,Py_GetCompiler,3.2,
function,Py_GetCopyright,3.2,

2
Misc/NEWS.d/next/Documentation/2021-06-16-18-09-49.bpo-44392.6RF1Sc.rst Normal file
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@ -0,0 +1,2 @@
Added a new section in the C API documentation for types used in type
hinting. Documented ``Py_GenericAlias`` and ``Py_GenericAliasType``.

2
Misc/stable_abi.txt
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@ -2043,7 +2043,7 @@ function Py_LeaveRecursiveCall
added 3.9
function Py_GenericAlias
added 3.9
function Py_GenericAliasType
data Py_GenericAliasType
added 3.9
function PyCMethod_New
added 3.9 # Windows: 3.10 & 3.9.2 -- https://bugs.python.org/issue43155

2
PC/python3dll.c
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@ -56,7 +56,6 @@ EXPORT_FUNC(Py_FatalError)
EXPORT_FUNC(Py_Finalize)
EXPORT_FUNC(Py_FinalizeEx)
EXPORT_FUNC(Py_GenericAlias)
EXPORT_FUNC(Py_GenericAliasType)
EXPORT_FUNC(Py_GetArgcArgv)
EXPORT_FUNC(Py_GetBuildInfo)
EXPORT_FUNC(Py_GetCompiler)
@ -722,6 +721,7 @@ EXPORT_DATA(_PyWeakref_ProxyType)
EXPORT_DATA(_PyWeakref_RefType)
EXPORT_DATA(Py_FileSystemDefaultEncodeErrors)
EXPORT_DATA(Py_FileSystemDefaultEncoding)
EXPORT_DATA(Py_GenericAliasType)
EXPORT_DATA(Py_HasFileSystemDefaultEncoding)
EXPORT_DATA(Py_UTF8Mode)
EXPORT_DATA(PyBaseObject_Type)