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