cpython/Doc/c-api/module.rst

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.. highlightlang:: c
.. _moduleobjects:
Module Objects
--------------
.. index:: object: module
There are only a few functions special to module objects.
.. cvar:: PyTypeObject PyModule_Type
.. index:: single: ModuleType (in module types)
This instance of :ctype:`PyTypeObject` represents the Python module type. This
is exposed to Python programs as ``types.ModuleType``.
.. cfunction:: int PyModule_Check(PyObject *p)
Return true if *p* is a module object, or a subtype of a module object.
.. cfunction:: int PyModule_CheckExact(PyObject *p)
Return true if *p* is a module object, but not a subtype of
:cdata:`PyModule_Type`.
.. cfunction:: PyObject* PyModule_New(const char *name)
.. index::
single: __name__ (module attribute)
single: __doc__ (module attribute)
single: __file__ (module attribute)
Return a new module object with the :attr:`__name__` attribute set to *name*.
Only the module's :attr:`__doc__` and :attr:`__name__` attributes are filled in;
the caller is responsible for providing a :attr:`__file__` attribute.
.. cfunction:: PyObject* PyModule_GetDict(PyObject *module)
.. index:: single: __dict__ (module attribute)
Return the dictionary object that implements *module*'s namespace; this object
is the same as the :attr:`__dict__` attribute of the module object. This
function never fails. It is recommended extensions use other
:cfunc:`PyModule_\*` and :cfunc:`PyObject_\*` functions rather than directly
manipulate a module's :attr:`__dict__`.
.. cfunction:: char* PyModule_GetName(PyObject *module)
.. index::
single: __name__ (module attribute)
single: SystemError (built-in exception)
Return *module*'s :attr:`__name__` value. If the module does not provide one,
or if it is not a string, :exc:`SystemError` is raised and *NULL* is returned.
.. cfunction:: char* PyModule_GetFilename(PyObject *module)
.. index::
single: __file__ (module attribute)
single: SystemError (built-in exception)
Return the name of the file from which *module* was loaded using *module*'s
:attr:`__file__` attribute. If this is not defined, or if it is not a string,
raise :exc:`SystemError` and return *NULL*.
.. cfunction:: void* PyModule_GetState(PyObject *module)
Return the "state" of the module, that is, a pointer to the block of memory
allocated at module creation time, or *NULL*. See
:cmember:`PyModuleDef.m_size`.
.. cfunction:: PyModuleDef* PyModule_GetDef(PyObject *module)
Return a pointer to the :ctype:`PyModuleDef` struct from which the module was
created, or *NULL* if the module wasn't created with
:cfunc:`PyModule_Create`.
Initializing C modules
^^^^^^^^^^^^^^^^^^^^^^
These functions are usually used in the module initialization function.
.. cfunction:: PyObject* PyModule_Create(PyModuleDef *module)
Create a new module object, given the definition in *module*. This behaves
like :cfunc:`PyModule_Create2` with *module_api_version* set to
:const:`PYTHON_API_VERSION`.
.. cfunction:: PyObject* PyModule_Create2(PyModuleDef *module, int module_api_version)
Create a new module object, given the definition in *module*, assuming the
API version *module_api_version*. If that version does not match the version
of the running interpreter, a :exc:`RuntimeWarning` is emitted.
.. note::
Most uses of this function should be using :cfunc:`PyModule_Create`
instead; only use this if you are sure you need it.
.. ctype:: PyModuleDef
This struct holds all information that is needed to create a module object.
There is usually only one static variable of that type for each module, which
is statically initialized and then passed to :cfunc:`PyModule_Create` in the
module initialization function.
.. cmember:: PyModuleDef_Base m_base
Always initialize this member to :const:`PyModuleDef_HEAD_INIT`.
.. cmember:: char* m_name
Name for the new module.
.. cmember:: char* m_doc
Docstring for the module; usually a docstring variable created with
:cfunc:`PyDoc_STRVAR` is used.
.. cmember:: Py_ssize_t m_size
If the module object needs additional memory, this should be set to the
number of bytes to allocate; a pointer to the block of memory can be
retrieved with :cfunc:`PyModule_GetState`. If no memory is needed, set
this to ``-1``.
This memory should be used, rather than static globals, to hold per-module
state, since it is then safe for use in multiple sub-interpreters. It is
freed when the module object is deallocated, after the :cmember:`m_free`
function has been called, if present.
.. cmember:: PyMethodDef* m_methods
A pointer to a table of module-level functions, described by
:ctype:`PyMethodDef` values. Can be *NULL* if no functions are present.
.. cmember:: inquiry m_reload
Currently unused, should be *NULL*.
.. cmember:: traverseproc m_traverse
A traversal function to call during GC traversal of the module object, or
*NULL* if not needed.
.. cmember:: inquiry m_clear
A clear function to call during GC clearing of the module object, or
*NULL* if not needed.
.. cmember:: freefunc m_free
A function to call during deallocation of the module object, or *NULL* if
not needed.
.. cfunction:: int PyModule_AddObject(PyObject *module, const char *name, PyObject *value)
Add an object to *module* as *name*. This is a convenience function which can
be used from the module's initialization function. This steals a reference to
*value*. Return ``-1`` on error, ``0`` on success.
.. cfunction:: int PyModule_AddIntConstant(PyObject *module, const char *name, long value)
Add an integer constant to *module* as *name*. This convenience function can be
used from the module's initialization function. Return ``-1`` on error, ``0`` on
success.
.. cfunction:: int PyModule_AddStringConstant(PyObject *module, const char *name, const char *value)
Add a string constant to *module* as *name*. This convenience function can be
used from the module's initialization function. The string *value* must be
null-terminated. Return ``-1`` on error, ``0`` on success.
.. cfunction:: int PyModule_AddIntMacro(PyObject *module, macro)
Add an int constant to *module*. The name and the value are taken from
*macro*. For example ``PyModule_AddConstant(module, AF_INET)`` adds the int
constant *AF_INET* with the value of *AF_INET* to *module*.
Return ``-1`` on error, ``0`` on success.
.. cfunction:: int PyModule_AddStringMacro(PyObject *module, macro)
Add a string constant to *module*.