1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
|
.. highlight:: c
.. _capsules:
Capsules
--------
.. index:: object: Capsule
Refer to :ref:`using-capsules` for more information on using these objects.
.. versionadded:: 3.1
.. c:type:: PyCapsule
This subtype of :c:type:`PyObject` represents an opaque value, useful for C
extension modules who need to pass an opaque value (as a :c:expr:`void*`
pointer) through Python code to other C code. It is often used to make a C
function pointer defined in one module available to other modules, so the
regular import mechanism can be used to access C APIs defined in dynamically
loaded modules.
.. c:type:: PyCapsule_Destructor
The type of a destructor callback for a capsule. Defined as::
typedef void (*PyCapsule_Destructor)(PyObject *);
See :c:func:`PyCapsule_New` for the semantics of PyCapsule_Destructor
callbacks.
.. c:function:: int PyCapsule_CheckExact(PyObject *p)
Return true if its argument is a :c:type:`PyCapsule`. This function always
succeeds.
.. c:function:: PyObject* PyCapsule_New(void *pointer, const char *name, PyCapsule_Destructor destructor)
Create a :c:type:`PyCapsule` encapsulating the *pointer*. The *pointer*
argument may not be ``NULL``.
On failure, set an exception and return ``NULL``.
The *name* string may either be ``NULL`` or a pointer to a valid C string. If
non-``NULL``, this string must outlive the capsule. (Though it is permitted to
free it inside the *destructor*.)
If the *destructor* argument is not ``NULL``, it will be called with the
capsule as its argument when it is destroyed.
If this capsule will be stored as an attribute of a module, the *name* should
be specified as ``modulename.attributename``. This will enable other modules
to import the capsule using :c:func:`PyCapsule_Import`.
.. c:function:: void* PyCapsule_GetPointer(PyObject *capsule, const char *name)
Retrieve the *pointer* stored in the capsule. On failure, set an exception
and return ``NULL``.
The *name* parameter must compare exactly to the name stored in the capsule.
If the name stored in the capsule is ``NULL``, the *name* passed in must also
be ``NULL``. Python uses the C function :c:func:`strcmp` to compare capsule
names.
.. c:function:: PyCapsule_Destructor PyCapsule_GetDestructor(PyObject *capsule)
Return the current destructor stored in the capsule. On failure, set an
exception and return ``NULL``.
It is legal for a capsule to have a ``NULL`` destructor. This makes a ``NULL``
return code somewhat ambiguous; use :c:func:`PyCapsule_IsValid` or
:c:func:`PyErr_Occurred` to disambiguate.
.. c:function:: void* PyCapsule_GetContext(PyObject *capsule)
Return the current context stored in the capsule. On failure, set an
exception and return ``NULL``.
It is legal for a capsule to have a ``NULL`` context. This makes a ``NULL``
return code somewhat ambiguous; use :c:func:`PyCapsule_IsValid` or
:c:func:`PyErr_Occurred` to disambiguate.
.. c:function:: const char* PyCapsule_GetName(PyObject *capsule)
Return the current name stored in the capsule. On failure, set an exception
and return ``NULL``.
It is legal for a capsule to have a ``NULL`` name. This makes a ``NULL`` return
code somewhat ambiguous; use :c:func:`PyCapsule_IsValid` or
:c:func:`PyErr_Occurred` to disambiguate.
.. c:function:: void* PyCapsule_Import(const char *name, int no_block)
Import a pointer to a C object from a capsule attribute in a module. The
*name* parameter should specify the full name to the attribute, as in
``module.attribute``. The *name* stored in the capsule must match this
string exactly.
Return the capsule's internal *pointer* on success. On failure, set an
exception and return ``NULL``.
.. versionchanged:: 3.3
*no_block* has no effect anymore.
.. c:function:: int PyCapsule_IsValid(PyObject *capsule, const char *name)
Determines whether or not *capsule* is a valid capsule. A valid capsule is
non-``NULL``, passes :c:func:`PyCapsule_CheckExact`, has a non-``NULL`` pointer
stored in it, and its internal name matches the *name* parameter. (See
:c:func:`PyCapsule_GetPointer` for information on how capsule names are
compared.)
In other words, if :c:func:`PyCapsule_IsValid` returns a true value, calls to
any of the accessors (any function starting with :c:func:`PyCapsule_Get`) are
guaranteed to succeed.
Return a nonzero value if the object is valid and matches the name passed in.
Return ``0`` otherwise. This function will not fail.
.. c:function:: int PyCapsule_SetContext(PyObject *capsule, void *context)
Set the context pointer inside *capsule* to *context*.
Return ``0`` on success. Return nonzero and set an exception on failure.
.. c:function:: int PyCapsule_SetDestructor(PyObject *capsule, PyCapsule_Destructor destructor)
Set the destructor inside *capsule* to *destructor*.
Return ``0`` on success. Return nonzero and set an exception on failure.
.. c:function:: int PyCapsule_SetName(PyObject *capsule, const char *name)
Set the name inside *capsule* to *name*. If non-``NULL``, the name must
outlive the capsule. If the previous *name* stored in the capsule was not
``NULL``, no attempt is made to free it.
Return ``0`` on success. Return nonzero and set an exception on failure.
.. c:function:: int PyCapsule_SetPointer(PyObject *capsule, void *pointer)
Set the void pointer inside *capsule* to *pointer*. The pointer may not be
``NULL``.
Return ``0`` on success. Return nonzero and set an exception on failure.
|
