Function Objects
****************

There are a few functions specific to Python functions.

type PyFunctionObject

   The C structure used for functions.

PyTypeObject PyFunction_Type

   This is an instance of "PyTypeObject" and represents the Python
   function type.  It is exposed to Python programmers as
   "types.FunctionType".

int PyFunction_Check(PyObject *o)

   Return true if *o* is a function object (has type
   "PyFunction_Type"). The parameter must not be "NULL".  This
   function always succeeds.

PyObject *PyFunction_New(PyObject *code, PyObject *globals)
    *Return value: New reference.*

   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. "__module__" is retrieved from *globals*. The argument
   defaults, annotations and closure are set to "NULL". "__qualname__"
   is set to the same value as the code object's "co_qualname" field.

PyObject *PyFunction_NewWithQualName(PyObject *code, PyObject *globals, PyObject *qualname)
    *Return value: New reference.*

   As "PyFunction_New()", but also allows setting the function
   object's "__qualname__" attribute. *qualname* should be a unicode
   object or "NULL"; if "NULL", the "__qualname__" attribute is set to
   the same value as the code object's "co_qualname" field.

   Added in version 3.3.

PyObject *PyFunction_GetCode(PyObject *op)
    *Return value: Borrowed reference.*

   Return the code object associated with the function object *op*.

PyObject *PyFunction_GetGlobals(PyObject *op)
    *Return value: Borrowed reference.*

   Return the globals dictionary associated with the function object
   *op*.

PyObject *PyFunction_GetModule(PyObject *op)
    *Return value: Borrowed reference.*

   Return a *borrowed reference* to the "__module__" attribute of the
   function object *op*. It can be *NULL*.

   This is normally a "string" containing the module name, but can be
   set to any other object by Python code.

PyObject *PyFunction_GetDefaults(PyObject *op)
    *Return value: Borrowed reference.*

   Return the argument default values of the function object *op*.
   This can be a tuple of arguments or "NULL".

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 "SystemError" and returns "-1" on failure.

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!

   Added in version 3.12.

PyObject *PyFunction_GetKwDefaults(PyObject *op)
    *Return value: Borrowed reference.*

   Return the keyword-only argument default values of the function
   object *op*. This can be a dictionary of arguments or "NULL".

int PyFunction_SetKwDefaults(PyObject *op, PyObject *defaults)

   Set the keyword-only argument default values of the function object
   *op*. *defaults* must be a dictionary of keyword-only arguments or
   "Py_None".

   This function returns "0" on success, and returns "-1" with an
   exception set on failure.

PyObject *PyFunction_GetClosure(PyObject *op)
    *Return value: Borrowed reference.*

   Return the closure associated with the function object *op*. This
   can be "NULL" or a tuple of cell objects.

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 "SystemError" and returns "-1" on failure.

PyObject *PyFunction_GetAnnotations(PyObject *op)
    *Return value: Borrowed reference.*

   Return the annotations of the function object *op*. This can be a
   mutable dictionary or "NULL".

int PyFunction_SetAnnotations(PyObject *op, PyObject *annotations)

   Set the annotations for the function object *op*. *annotations*
   must be a dictionary or "Py_None".

   Raises "SystemError" and returns "-1" on failure.

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)
    *Return value: Borrowed reference.*

   These functions are similar to their "PyFunction_Get*"
   counterparts, but do not do type checking. Passing anything other
   than an instance of "PyFunction_Type" is undefined behavior.

int PyFunction_AddWatcher(PyFunction_WatchCallback callback)

   Register *callback* as a function watcher for the current
   interpreter. Return an ID which may be passed to
   "PyFunction_ClearWatcher()". In case of error (e.g. no more watcher
   IDs available), return "-1" and set an exception.

   Added in version 3.12.

int PyFunction_ClearWatcher(int watcher_id)

   Clear watcher identified by *watcher_id* previously returned from
   "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.)

   Added in version 3.12.

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"

   Added in version 3.12:

   * "PyFunction_PYFUNC_EVENT_MODIFY_QUALNAME"

   Added in version 3.15.

typedef 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 *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
   "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.

   Added in version 3.12.
