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+++ b/symbian-qemu-0.9.1-12/python-2.6.1/Doc/c-api/import.rst Fri Jul 31 15:01:17 2009 +0100
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+.. highlightlang:: c
+
+.. _importing:
+
+Importing Modules
+=================
+
+
+.. cfunction:: PyObject* PyImport_ImportModule(const char *name)
+
+ .. index::
+ single: package variable; __all__
+ single: __all__ (package variable)
+ single: modules (in module sys)
+
+ This is a simplified interface to :cfunc:`PyImport_ImportModuleEx` below,
+ leaving the *globals* and *locals* arguments set to *NULL* and *level* set
+ to 0. When the *name*
+ argument contains a dot (when it specifies a submodule of a package), the
+ *fromlist* argument is set to the list ``['*']`` so that the return value is the
+ named module rather than the top-level package containing it as would otherwise
+ be the case. (Unfortunately, this has an additional side effect when *name* in
+ fact specifies a subpackage instead of a submodule: the submodules specified in
+ the package's ``__all__`` variable are loaded.) Return a new reference to the
+ imported module, or *NULL* with an exception set on failure. Before Python 2.4,
+ the module may still be created in the failure case --- examine ``sys.modules``
+ to find out. Starting with Python 2.4, a failing import of a module no longer
+ leaves the module in ``sys.modules``.
+
+ .. versionchanged:: 2.4
+ failing imports remove incomplete module objects.
+
+ .. versionchanged:: 2.6
+ always use absolute imports
+
+
+.. cfunction:: PyObject* PyImport_ImportModuleNoBlock(const char *name)
+
+ This version of :cfunc:`PyImport_ImportModule` does not block. It's intended
+ to be used in C functions that import other modules to execute a function.
+ The import may block if another thread holds the import lock. The function
+ :cfunc:`PyImport_ImportModuleNoBlock` never blocks. It first tries to fetch
+ the module from sys.modules and falls back to :cfunc:`PyImport_ImportModule`
+ unless the lock is held, in which case the function will raise an
+ :exc:`ImportError`.
+
+ .. versionadded:: 2.6
+
+
+.. cfunction:: PyObject* PyImport_ImportModuleEx(char *name, PyObject *globals, PyObject *locals, PyObject *fromlist)
+
+ .. index:: builtin: __import__
+
+ Import a module. This is best described by referring to the built-in Python
+ function :func:`__import__`, as the standard :func:`__import__` function calls
+ this function directly.
+
+ The return value is a new reference to the imported module or top-level package,
+ or *NULL* with an exception set on failure (before Python 2.4, the module may
+ still be created in this case). Like for :func:`__import__`, the return value
+ when a submodule of a package was requested is normally the top-level package,
+ unless a non-empty *fromlist* was given.
+
+ .. versionchanged:: 2.4
+ failing imports remove incomplete module objects.
+
+ .. versionchanged:: 2.6
+ The function is an alias for :cfunc:`PyImport_ImportModuleLevel` with
+ -1 as level, meaning relative import.
+
+
+.. cfunction:: PyObject* PyImport_ImportModuleLevel(char *name, PyObject *globals, PyObject *locals, PyObject *fromlist, int level)
+
+ Import a module. This is best described by referring to the built-in Python
+ function :func:`__import__`, as the standard :func:`__import__` function calls
+ this function directly.
+
+ The return value is a new reference to the imported module or top-level package,
+ or *NULL* with an exception set on failure. Like for :func:`__import__`,
+ the return value when a submodule of a package was requested is normally the
+ top-level package, unless a non-empty *fromlist* was given.
+
+ .. versionadded:: 2.5
+
+
+.. cfunction:: PyObject* PyImport_Import(PyObject *name)
+
+ .. index::
+ module: rexec
+ module: ihooks
+
+ This is a higher-level interface that calls the current "import hook function".
+ It invokes the :func:`__import__` function from the ``__builtins__`` of the
+ current globals. This means that the import is done using whatever import hooks
+ are installed in the current environment, e.g. by :mod:`rexec` or :mod:`ihooks`.
+
+ .. versionchanged:: 2.6
+ always use absolute imports
+
+
+.. cfunction:: PyObject* PyImport_ReloadModule(PyObject *m)
+
+ .. index:: builtin: reload
+
+ Reload a module. This is best described by referring to the built-in Python
+ function :func:`reload`, as the standard :func:`reload` function calls this
+ function directly. Return a new reference to the reloaded module, or *NULL*
+ with an exception set on failure (the module still exists in this case).
+
+
+.. cfunction:: PyObject* PyImport_AddModule(const char *name)
+
+ Return the module object corresponding to a module name. The *name* argument
+ may be of the form ``package.module``. First check the modules dictionary if
+ there's one there, and if not, create a new one and insert it in the modules
+ dictionary. Return *NULL* with an exception set on failure.
+
+ .. note::
+
+ This function does not load or import the module; if the module wasn't already
+ loaded, you will get an empty module object. Use :cfunc:`PyImport_ImportModule`
+ or one of its variants to import a module. Package structures implied by a
+ dotted name for *name* are not created if not already present.
+
+
+.. cfunction:: PyObject* PyImport_ExecCodeModule(char *name, PyObject *co)
+
+ .. index:: builtin: compile
+
+ Given a module name (possibly of the form ``package.module``) and a code object
+ read from a Python bytecode file or obtained from the built-in function
+ :func:`compile`, load the module. Return a new reference to the module object,
+ or *NULL* with an exception set if an error occurred. Before Python 2.4, the
+ module could still be created in error cases. Starting with Python 2.4, *name*
+ is removed from :attr:`sys.modules` in error cases, and even if *name* was already
+ in :attr:`sys.modules` on entry to :cfunc:`PyImport_ExecCodeModule`. Leaving
+ incompletely initialized modules in :attr:`sys.modules` is dangerous, as imports of
+ such modules have no way to know that the module object is an unknown (and
+ probably damaged with respect to the module author's intents) state.
+
+ This function will reload the module if it was already imported. See
+ :cfunc:`PyImport_ReloadModule` for the intended way to reload a module.
+
+ If *name* points to a dotted name of the form ``package.module``, any package
+ structures not already created will still not be created.
+
+ .. versionchanged:: 2.4
+ *name* is removed from :attr:`sys.modules` in error cases.
+
+
+.. cfunction:: long PyImport_GetMagicNumber()
+
+ Return the magic number for Python bytecode files (a.k.a. :file:`.pyc` and
+ :file:`.pyo` files). The magic number should be present in the first four bytes
+ of the bytecode file, in little-endian byte order.
+
+
+.. cfunction:: PyObject* PyImport_GetModuleDict()
+
+ Return the dictionary used for the module administration (a.k.a.
+ ``sys.modules``). Note that this is a per-interpreter variable.
+
+
+.. cfunction:: PyObject* PyImport_GetImporter(PyObject *path)
+
+ Return an importer object for a :data:`sys.path`/:attr:`pkg.__path__` item
+ *path*, possibly by fetching it from the :data:`sys.path_importer_cache`
+ dict. If it wasn't yet cached, traverse :data:`sys.path_hooks` until a hook
+ is found that can handle the path item. Return ``None`` if no hook could;
+ this tells our caller it should fall back to the builtin import mechanism.
+ Cache the result in :data:`sys.path_importer_cache`. Return a new reference
+ to the importer object.
+
+ .. versionadded:: 2.6
+
+
+.. cfunction:: void _PyImport_Init()
+
+ Initialize the import mechanism. For internal use only.
+
+
+.. cfunction:: void PyImport_Cleanup()
+
+ Empty the module table. For internal use only.
+
+
+.. cfunction:: void _PyImport_Fini()
+
+ Finalize the import mechanism. For internal use only.
+
+
+.. cfunction:: PyObject* _PyImport_FindExtension(char *, char *)
+
+ For internal use only.
+
+
+.. cfunction:: PyObject* _PyImport_FixupExtension(char *, char *)
+
+ For internal use only.
+
+
+.. cfunction:: int PyImport_ImportFrozenModule(char *name)
+
+ Load a frozen module named *name*. Return ``1`` for success, ``0`` if the
+ module is not found, and ``-1`` with an exception set if the initialization
+ failed. To access the imported module on a successful load, use
+ :cfunc:`PyImport_ImportModule`. (Note the misnomer --- this function would
+ reload the module if it was already imported.)
+
+
+.. ctype:: struct _frozen
+
+ .. index:: single: freeze utility
+
+ This is the structure type definition for frozen module descriptors, as
+ generated by the :program:`freeze` utility (see :file:`Tools/freeze/` in the
+ Python source distribution). Its definition, found in :file:`Include/import.h`,
+ is::
+
+ struct _frozen {
+ char *name;
+ unsigned char *code;
+ int size;
+ };
+
+
+.. cvar:: struct _frozen* PyImport_FrozenModules
+
+ This pointer is initialized to point to an array of :ctype:`struct _frozen`
+ records, terminated by one whose members are all *NULL* or zero. When a frozen
+ module is imported, it is searched in this table. Third-party code could play
+ tricks with this to provide a dynamically created collection of frozen modules.
+
+
+.. cfunction:: int PyImport_AppendInittab(char *name, void (*initfunc)(void))
+
+ Add a single module to the existing table of built-in modules. This is a
+ convenience wrapper around :cfunc:`PyImport_ExtendInittab`, returning ``-1`` if
+ the table could not be extended. The new module can be imported by the name
+ *name*, and uses the function *initfunc* as the initialization function called
+ on the first attempted import. This should be called before
+ :cfunc:`Py_Initialize`.
+
+
+.. ctype:: struct _inittab
+
+ Structure describing a single entry in the list of built-in modules. Each of
+ these structures gives the name and initialization function for a module built
+ into the interpreter. Programs which embed Python may use an array of these
+ structures in conjunction with :cfunc:`PyImport_ExtendInittab` to provide
+ additional built-in modules. The structure is defined in
+ :file:`Include/import.h` as::
+
+ struct _inittab {
+ char *name;
+ void (*initfunc)(void);
+ };
+
+
+.. cfunction:: int PyImport_ExtendInittab(struct _inittab *newtab)
+
+ Add a collection of modules to the table of built-in modules. The *newtab*
+ array must end with a sentinel entry which contains *NULL* for the :attr:`name`
+ field; failure to provide the sentinel value can result in a memory fault.
+ Returns ``0`` on success or ``-1`` if insufficient memory could be allocated to
+ extend the internal table. In the event of failure, no modules are added to the
+ internal table. This should be called before :cfunc:`Py_Initialize`.