.. highlightlang:: c .. _moduleobjects: Module Objects -------------- .. index:: object: module .. c:var:: PyTypeObject PyModule_Type .. index:: single: ModuleType (in module types) This instance of :c:type:`PyTypeObject` represents the Python module type. This is exposed to Python programs as ``types.ModuleType``. .. c:function:: int PyModule_Check(PyObject *p) Return true if *p* is a module object, or a subtype of a module object. .. c:function:: int PyModule_CheckExact(PyObject *p) Return true if *p* is a module object, but not a subtype of :c:data:`PyModule_Type`. .. c:function:: PyObject* PyModule_NewObject(PyObject *name) .. index:: single: __name__ (module attribute) single: __doc__ (module attribute) single: __file__ (module attribute) single: __package__ (module attribute) single: __loader__ (module attribute) Return a new module object with the :attr:`__name__` attribute set to *name*. The module's :attr:`__name__`, :attr:`__doc__`, :attr:`__package__`, and :attr:`__loader__` attributes are filled in (all but :attr:`__name__` are set to ``None``); the caller is responsible for providing a :attr:`__file__` attribute. .. versionadded:: 3.3 .. versionchanged:: 3.4 :attr:`__package__` and :attr:`__loader__` are set to ``None``. .. c:function:: PyObject* PyModule_New(const char *name) Similar to :c:func:`PyImport_NewObject`, but the name is an UTF-8 encoded string instead of a Unicode object. .. c:function:: 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 :c:func:`PyModule_\*` and :c:func:`PyObject_\*` functions rather than directly manipulate a module's :attr:`__dict__`. .. c:function:: PyObject* PyModule_GetNameObject(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. .. versionadded:: 3.3 .. c:function:: char* PyModule_GetName(PyObject *module) Similar to :c:func:`PyModule_GetNameObject` but return the name encoded to ``'utf-8'``. .. c:function:: PyObject* PyModule_GetFilenameObject(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 unicode string, raise :exc:`SystemError` and return *NULL*; otherwise return a reference to a Unicode object. .. versionadded:: 3.2 .. c:function:: char* PyModule_GetFilename(PyObject *module) Similar to :c:func:`PyModule_GetFilenameObject` but return the filename encoded to 'utf-8'. .. deprecated:: 3.2 :c:func:`PyModule_GetFilename` raises :c:type:`UnicodeEncodeError` on unencodable filenames, use :c:func:`PyModule_GetFilenameObject` instead. Per-interpreter module state ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Single-phase initialization creates singleton modules that can store additional information as part of the interpreter, allow that state to be retrieved later with only a reference to the module definition, rather than to the module itself. .. c:function:: 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 :c:member:`PyModuleDef.m_size`. .. c:function:: PyModuleDef* PyModule_GetDef(PyObject *module) Return a pointer to the :c:type:`PyModuleDef` struct from which the module was created, or *NULL* if the module wasn't created with :c:func:`PyModule_Create`. .. c:function:: PyObject* PyState_FindModule(PyModuleDef *def) Returns the module object that was created from *def* for the current interpreter. This method requires that the module object has been attached to the interpreter state with :c:func:`PyState_AddModule` beforehand. In case the corresponding module object is not found or has not been attached to the interpreter state yet, it returns NULL. .. c:function:: int PyState_AddModule(PyObject *module, PyModuleDef *def) Attaches the module object passed to the function to the interpreter state. This allows the module object to be accessible via :c:func:`PyState_FindModule`. .. versionadded:: 3.3 .. c:function:: int PyState_RemoveModule(PyModuleDef *def) Removes the module object created from *def* from the interpreter state. .. versionadded:: 3.3 Initializing C modules ^^^^^^^^^^^^^^^^^^^^^^ .. c:type:: 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 :c:func:`PyModule_Create` in the module initialization function. .. c:member:: PyModuleDef_Base m_base Always initialize this member to :const:`PyModuleDef_HEAD_INIT`. .. c:member:: char* m_name Name for the new module. .. c:member:: char* m_doc Docstring for the module; usually a docstring variable created with :c:func:`PyDoc_STRVAR` is used. .. c:member:: Py_ssize_t m_size Some modules allow re-initialization (calling their ``PyInit_*`` function more than once). These modules should keep their state in a per-module memory area that can be retrieved with :c:func:`PyModule_GetState`. 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 :c:member:`m_free` function has been called, if present. Setting ``m_size`` to ``-1`` means that the module can not be re-initialized because it has global state. Setting it to a non-negative value means that the module can be re-initialized and specifies the additional amount of memory it requires for its state. See :PEP:`3121` for more details. .. c:member:: PyMethodDef* m_methods A pointer to a table of module-level functions, described by :c:type:`PyMethodDef` values. Can be *NULL* if no functions are present. .. c:member:: PyModuleDef_Slot* m_slots An array of slot definitions for multi-phase initialization, terminated by a *NULL* entry. .. c:member:: traverseproc m_traverse A traversal function to call during GC traversal of the module object, or *NULL* if not needed. .. c:member:: inquiry m_clear A clear function to call during GC clearing of the module object, or *NULL* if not needed. .. c:member:: freefunc m_free A function to call during deallocation of the module object, or *NULL* if not needed. The module initialization function may create and return the module object directly. This is referred to as "single-phase initialization", and uses one of the following two module creation functions: .. c:function:: PyObject* PyModule_Create(PyModuleDef *module) Create a new module object, given the definition in *module*. This behaves like :c:func:`PyModule_Create2` with *module_api_version* set to :const:`PYTHON_API_VERSION`. .. c:function:: 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 :c:func:`PyModule_Create` instead; only use this if you are sure you need it. Alternatively, the module initialization function may instead return a :c:type:`PyModuleDef` instance with a non-empty ``m_slots`` array. This is referred to as "multi-phase initialization", and ``PyModuleDef`` instance should be initialized with the following function: .. c:function:: PyObject* PyModuleDef_Init(PyModuleDef *module) Ensures a module definition is a properly initialized Python object that correctly reports its type and reference count. .. XXX (ncoghlan): It's not clear if it makes sense to document PyModule_ExecDef PyModule_FromDefAndSpec or PyModule_FromDefAndSpec2 here, as end user code generally shouldn't be calling those. The module initialization function (if using single phase initialization) or a function called from a module execution slot (if using multiphase initialization), can use the following functions to help initialize the module state: .. c:function:: int PyModule_SetDocString(PyObject *module, const char *docstring) Set the docstring for *module* to *docstring*. Return ``-1`` on error, ``0`` on success. .. c:function:: int PyModule_AddFunctions(PyObject *module, PyMethodDef *functions) Add the functions from the ``NULL`` terminated *functions* array to *module*. Refer to the :c:type:`PyMethodDef` documentation for details on individual entries (due to the lack of a shared module namespace, module level "functions" implemented in C typically receive the module as their first parameter, making them similar to instance methods on Python classes). .. c:function:: 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. .. c:function:: 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. .. c:function:: 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. .. c:function:: int PyModule_AddIntMacro(PyObject *module, macro) Add an int constant to *module*. The name and the value are taken from *macro*. For example ``PyModule_AddIntMacro(module, AF_INET)`` adds the int constant *AF_INET* with the value of *AF_INET* to *module*. Return ``-1`` on error, ``0`` on success. .. c:function:: int PyModule_AddStringMacro(PyObject *module, macro) Add a string constant to *module*.