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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215
|
.. highlight:: c
.. _function-objects:
Function Objects
----------------
.. index:: pair: object; function
There are a few functions specific to Python functions.
.. c:type:: PyFunctionObject
The C structure used for functions.
.. c:var:: PyTypeObject PyFunction_Type
.. index:: single: MethodType (in module types)
This is an instance of :c:type:`PyTypeObject` and represents the Python function
type. It is exposed to Python programmers as ``types.FunctionType``.
.. c:function:: int PyFunction_Check(PyObject *o)
Return true if *o* is a function object (has type :c:data:`PyFunction_Type`).
The parameter must not be ``NULL``. This function always succeeds.
.. c:function:: PyObject* PyFunction_New(PyObject *code, PyObject *globals)
Return a new function object associated with the code object *code*. *globals*
must be a dictionary with the global variables accessible to the function.
The function's docstring and name are retrieved from the code object.
:attr:`~function.__module__`
is retrieved from *globals*. The argument defaults, annotations and closure are
set to ``NULL``. :attr:`~function.__qualname__` is set to the same value as
the code object's :attr:`~codeobject.co_qualname` field.
.. c:function:: PyObject* PyFunction_NewWithQualName(PyObject *code, PyObject *globals, PyObject *qualname)
As :c:func:`PyFunction_New`, but also allows setting the function object's
:attr:`~function.__qualname__` attribute.
*qualname* should be a unicode object or ``NULL``;
if ``NULL``, the :attr:`!__qualname__` attribute is set to the same value as
the code object's :attr:`~codeobject.co_qualname` field.
.. versionadded:: 3.3
.. c:function:: PyObject* PyFunction_GetCode(PyObject *op)
Return the code object associated with the function object *op*.
.. c:function:: PyObject* PyFunction_GetGlobals(PyObject *op)
Return the globals dictionary associated with the function object *op*.
.. c:function:: PyObject* PyFunction_GetModule(PyObject *op)
Return a :term:`borrowed reference` to the :attr:`~function.__module__`
attribute of the :ref:`function object <user-defined-funcs>` *op*.
It can be *NULL*.
This is normally a :class:`string <str>` containing the module name,
but can be set to any other object by Python code.
.. c:function:: PyObject* PyFunction_GetDefaults(PyObject *op)
Return the argument default values of the function object *op*. This can be a
tuple of arguments or ``NULL``.
.. c:function:: int PyFunction_SetDefaults(PyObject *op, PyObject *defaults)
Set the argument default values for the function object *op*. *defaults* must be
``Py_None`` or a tuple.
Raises :exc:`SystemError` and returns ``-1`` on failure.
.. c:function:: void PyFunction_SetVectorcall(PyFunctionObject *func, vectorcallfunc vectorcall)
Set the vectorcall field of a given function object *func*.
Warning: extensions using this API must preserve the behavior
of the unaltered (default) vectorcall function!
.. versionadded:: 3.12
.. c:function:: PyObject* PyFunction_GetKwDefaults(PyObject *op)
Return the keyword-only argument default values of the function object *op*. This can be a
dictionary of arguments or ``NULL``.
.. c:function:: PyObject* PyFunction_GetClosure(PyObject *op)
Return the closure associated with the function object *op*. This can be ``NULL``
or a tuple of cell objects.
.. c:function:: int PyFunction_SetClosure(PyObject *op, PyObject *closure)
Set the closure associated with the function object *op*. *closure* must be
``Py_None`` or a tuple of cell objects.
Raises :exc:`SystemError` and returns ``-1`` on failure.
.. c:function:: PyObject *PyFunction_GetAnnotations(PyObject *op)
Return the annotations of the function object *op*. This can be a
mutable dictionary or ``NULL``.
.. c:function:: int PyFunction_SetAnnotations(PyObject *op, PyObject *annotations)
Set the annotations for the function object *op*. *annotations*
must be a dictionary or ``Py_None``.
Raises :exc:`SystemError` and returns ``-1`` on failure.
.. c:function:: PyObject *PyFunction_GET_CODE(PyObject *op)
PyObject *PyFunction_GET_GLOBALS(PyObject *op)
PyObject *PyFunction_GET_MODULE(PyObject *op)
PyObject *PyFunction_GET_DEFAULTS(PyObject *op)
PyObject *PyFunction_GET_KW_DEFAULTS(PyObject *op)
PyObject *PyFunction_GET_CLOSURE(PyObject *op)
PyObject *PyFunction_GET_ANNOTATIONS(PyObject *op)
These functions are similar to their ``PyFunction_Get*`` counterparts, but
do not do type checking. Passing anything other than an instance of
:c:data:`PyFunction_Type` is undefined behavior.
.. c:function:: int PyFunction_AddWatcher(PyFunction_WatchCallback callback)
Register *callback* as a function watcher for the current interpreter.
Return an ID which may be passed to :c:func:`PyFunction_ClearWatcher`.
In case of error (e.g. no more watcher IDs available),
return ``-1`` and set an exception.
.. versionadded:: 3.12
.. c:function:: int PyFunction_ClearWatcher(int watcher_id)
Clear watcher identified by *watcher_id* previously returned from
:c:func:`PyFunction_AddWatcher` for the current interpreter.
Return ``0`` on success, or ``-1`` and set an exception on error
(e.g. if the given *watcher_id* was never registered.)
.. versionadded:: 3.12
.. c:type:: PyFunction_WatchEvent
Enumeration of possible function watcher events:
- ``PyFunction_EVENT_CREATE``
- ``PyFunction_EVENT_DESTROY``
- ``PyFunction_EVENT_MODIFY_CODE``
- ``PyFunction_EVENT_MODIFY_DEFAULTS``
- ``PyFunction_EVENT_MODIFY_KWDEFAULTS``
.. versionadded:: 3.12
.. c:type:: int (*PyFunction_WatchCallback)(PyFunction_WatchEvent event, PyFunctionObject *func, PyObject *new_value)
Type of a function watcher callback function.
If *event* is ``PyFunction_EVENT_CREATE`` or ``PyFunction_EVENT_DESTROY``
then *new_value* will be ``NULL``. Otherwise, *new_value* will hold a
:term:`borrowed reference` to the new value that is about to be stored in
*func* for the attribute that is being modified.
The callback may inspect but must not modify *func*; doing so could have
unpredictable effects, including infinite recursion.
If *event* is ``PyFunction_EVENT_CREATE``, then the callback is invoked
after *func* has been fully initialized. Otherwise, the callback is invoked
before the modification to *func* takes place, so the prior state of *func*
can be inspected. The runtime is permitted to optimize away the creation of
function objects when possible. In such cases no event will be emitted.
Although this creates the possibility of an observable difference of
runtime behavior depending on optimization decisions, it does not change
the semantics of the Python code being executed.
If *event* is ``PyFunction_EVENT_DESTROY``, Taking a reference in the
callback to the about-to-be-destroyed function will resurrect it, preventing
it from being freed at this time. When the resurrected object is destroyed
later, any watcher callbacks active at that time will be called again.
If the callback sets an exception, it must return ``-1``; this exception will
be printed as an unraisable exception using :c:func:`PyErr_WriteUnraisable`.
Otherwise it should return ``0``.
There may already be a pending exception set on entry to the callback. In
this case, the callback should return ``0`` with the same exception still
set. This means the callback may not call any other API that can set an
exception unless it saves and clears the exception state first, and restores
it before returning.
.. versionadded:: 3.12
|