bpo-38787: C API for module state access from extension methods (PEP 573) (GH-19936)

Module C state is now accessible from C-defined heap type methods (PEP 573).
Patch by Marcel Plch and Petr Viktorin.

Co-authored-by: Marcel Plch <mplch@redhat.com>
Co-authored-by: Victor Stinner <vstinner@python.org>

Doc/c-api/structures.rst

@@ -147,23 +147,56 @@ Implementing functions and methods
    value of the function as exposed in Python.  The function must return a new
    reference.
 
+   The function signature is::
+
+      PyObject *PyCFunction(PyObject *self,
+                            PyObject *const *args);
 
 .. c:type:: PyCFunctionWithKeywords
 
    Type of the functions used to implement Python callables in C
    with signature :const:`METH_VARARGS | METH_KEYWORDS`.
+   The function signature is::
+
+      PyObject *PyCFunctionWithKeywords(PyObject *self,
+                                        PyObject *const *args,
+                                        PyObject *kwargs);
 
 
 .. c:type:: _PyCFunctionFast
 
    Type of the functions used to implement Python callables in C
    with signature :const:`METH_FASTCALL`.
+   The function signature is::
 
+      PyObject *_PyCFunctionFast(PyObject *self,
+                                 PyObject *const *args,
+                                 Py_ssize_t nargs);
 
 .. c:type:: _PyCFunctionFastWithKeywords
 
    Type of the functions used to implement Python callables in C
    with signature :const:`METH_FASTCALL | METH_KEYWORDS`.
+   The function signature is::
+
+      PyObject *_PyCFunctionFastWithKeywords(PyObject *self,
+                                             PyObject *const *args,
+                                             Py_ssize_t nargs,
+                                             PyObject *kwnames);
+
+.. c:type:: PyCMethod
+
+   Type of the functions used to implement Python callables in C
+   with signature :const:`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)
+
+   .. versionadded:: 3.9
 
 
 .. c:type:: PyMethodDef
@@ -197,9 +230,7 @@ The :attr:`ml_flags` field is a bitfield which can include the following flags.
 The individual flags indicate either a calling convention or a binding
 convention.
 
-There are four basic calling conventions for positional arguments
-and two of them can be combined with :const:`METH_KEYWORDS` to support
-also keyword arguments.  So there are a total of 6 calling conventions:
+There are these calling conventions:
 
 .. data:: METH_VARARGS
 
@@ -250,6 +281,19 @@ also keyword arguments.  So there are a total of 6 calling conventions:
    .. versionadded:: 3.7
 
 
+.. data:: METH_METHOD | METH_FASTCALL | METH_KEYWORDS
+
+   Extension of :const:`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)``.
+
+   The method needs to be of type :c:type:`PyCMethod`, the same as for
+   ``METH_FASTCALL | METH_KEYWORDS`` with ``defining_class`` argument added after
+   ``self``.
+
+   .. versionadded:: 3.9
+
+
 .. data:: METH_NOARGS
 
    Methods without parameters don't need to check whether arguments are given if

Doc/c-api/type.rst

@@ -109,6 +109,30 @@ Type Objects
 
    .. versionadded:: 3.4
 
+.. 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``.
+
+   .. 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
 .............................
@@ -116,7 +140,7 @@ Creating Heap-Allocated Types
 The following functions and structs are used to create
 :ref:`heap types <heap-types>`.
 
-.. c:function:: PyObject* PyType_FromSpecWithBases(PyType_Spec *spec, PyObject *bases)
+.. 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`).
@@ -127,8 +151,18 @@ The following functions and structs are used to create
    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* 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`.
+
    This function calls :c:func:`PyType_Ready` on the new type.
 
+   .. versionadded:: 3.9
+
+.. 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)