.. highlight:: c

.. _importing:

Importing Modules

.. c:function:: PyObject* PyImport_ImportModule(const char *name)

.. index:: single: package variable; all single: all (package variable) single: modules (in module sys)

This is a wrapper around :c:func:PyImport_Import() which takes a :c:expr:const char * as an argument instead of a :c:expr:PyObject *.

.. c:function:: PyObject* PyImport_ImportModuleEx(const char *name, PyObject *globals, PyObject *locals, PyObject *fromlist)

.. index:: pair: built-in function; import

Import a module. This is best described by referring to the built-in Python function :func:__import__.

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.

Failing imports remove incomplete module objects, like with :c:func:PyImport_ImportModule.

.. c:function:: PyObject* PyImport_ImportModuleLevelObject(PyObject *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.

.. versionadded:: 3.3

.. c:function:: PyObject* PyImport_ImportModuleLevel(const char *name, PyObject *globals, PyObject *locals, PyObject *fromlist, int level)

Similar to :c:func:PyImport_ImportModuleLevelObject, but the name is a UTF-8 encoded string instead of a Unicode object.

.. versionchanged:: 3.3 Negative values for level are no longer accepted.

.. c:function:: PyObject* PyImport_Import(PyObject *name)

This is a higher-level interface that calls the current "import hook function" (with an explicit level of 0, meaning absolute import). 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.

This function always uses absolute imports.

.. c:function:: PyObject* PyImport_ReloadModule(PyObject *m)

Reload a module. Return a new reference to the reloaded module, or NULL with an exception set on failure (the module still exists in this case).

.. c:function:: PyObject* PyImport_AddModuleRef(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 a :term:strong reference to the module on success. Return NULL with an exception set on failure.

The module name name is decoded from UTF-8.

This function does not load or import the module; if the module wasn't already loaded, you will get an empty module object. Use :c:func: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.

.. versionadded:: 3.13

.. c:function:: PyObject* PyImport_AddModuleObject(PyObject *name)

Similar to :c:func:PyImport_AddModuleRef, but return a :term:borrowed reference and name is a Python :class:str object.

.. versionadded:: 3.3

.. c:function:: PyObject* PyImport_AddModule(const char *name)

Similar to :c:func:PyImport_AddModuleRef, but return a :term:borrowed reference.

.. c:function:: PyObject* PyImport_ExecCodeModule(const char *name, PyObject *co)

.. index:: pair: built-in function; 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. name is removed from :data:sys.modules in error cases, even if name was already in :data:sys.modules on entry to :c:func:PyImport_ExecCodeModule. Leaving incompletely initialized modules in :data: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.

The module's :attr:~module.__spec__ and :attr:~module.__loader__ will be set, if not set already, with the appropriate values. The spec's loader will be set to the module's :attr:!__loader__ (if set) and to an instance of :class:~importlib.machinery.SourceFileLoader otherwise.

The module's :attr:~module.__file__ attribute will be set to the code object's :attr:~codeobject.co_filename.

This function will reload the module if it was already imported. See :c:func: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.

See also :c:func:PyImport_ExecCodeModuleEx and :c:func:PyImport_ExecCodeModuleWithPathnames.

.. versionchanged:: 3.12 The setting of __cached__ and :attr:~module.__loader__ is deprecated. See :class:~importlib.machinery.ModuleSpec for alternatives.

.. versionchanged:: 3.15 __cached__ is no longer set.

.. c:function:: PyObject* PyImport_ExecCodeModuleEx(const char *name, PyObject *co, const char *pathname)

Like :c:func:PyImport_ExecCodeModule, but the :attr:~module.__file__ attribute of the module object is set to pathname if it is non-NULL.

See also :c:func:PyImport_ExecCodeModuleWithPathnames.

.. c:function:: PyObject* PyImport_ExecCodeModuleObject(PyObject *name, PyObject *co, PyObject *pathname, PyObject *cpathname)

Like :c:func:PyImport_ExecCodeModuleEx, but the path to any compiled file via cpathname is used appropriately when non-NULL. Of the three functions, this is the preferred one to use.

.. versionadded:: 3.3

.. versionchanged:: 3.12 Setting __cached__ is deprecated. See :class:~importlib.machinery.ModuleSpec for alternatives.

.. versionchanged:: 3.15 __cached__ no longer set.

.. c:function:: PyObject* PyImport_ExecCodeModuleWithPathnames(const char *name, PyObject *co, const char *pathname, const char *cpathname)

Like :c:func:PyImport_ExecCodeModuleObject, but name, pathname and cpathname are UTF-8 encoded strings. Attempts are also made to figure out what the value for pathname should be from cpathname if the former is set to NULL.

.. versionadded:: 3.2 .. versionchanged:: 3.3 Uses :func:!imp.source_from_cache in calculating the source path if only the bytecode path is provided. .. versionchanged:: 3.12 No longer uses the removed :mod:!imp module.

.. c:function:: long PyImport_GetMagicNumber()

Return the magic number for Python bytecode files (a.k.a. :file:.pyc file). The magic number should be present in the first four bytes of the bytecode file, in little-endian byte order. Returns -1 on error.

.. versionchanged:: 3.3 Return value of -1 upon failure.

.. c:function:: const char * PyImport_GetMagicTag()

Return the magic tag string for :pep:3147 format Python bytecode file names. Keep in mind that the value at sys.implementation.cache_tag is authoritative and should be used instead of this function.

.. versionadded:: 3.2

.. c:function:: PyObject* PyImport_GetModuleDict()

Return the dictionary used for the module administration (a.k.a. sys.modules). Note that this is a per-interpreter variable.

.. c:function:: PyObject* PyImport_GetModule(PyObject *name)

Return the already imported module with the given name. If the module has not been imported yet then returns NULL but does not set an error. Returns NULL and sets an error if the lookup failed.

.. versionadded:: 3.7

.. c:function:: PyObject* PyImport_GetImporter(PyObject *path)

Return a finder 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 that the :term:path based finder could not find a finder for this path item. Cache the result in :data:sys.path_importer_cache. Return a new reference to the finder object.

.. c:function:: int PyImport_ImportFrozenModuleObject(PyObject *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 :c:func:PyImport_ImportModule. (Note the misnomer --- this function would reload the module if it was already imported.)

.. versionadded:: 3.3

.. versionchanged:: 3.4 The __file__ attribute is no longer set on the module.

.. c:function:: int PyImport_ImportFrozenModule(const char *name)

Similar to :c:func:PyImport_ImportFrozenModuleObject, but the name is a UTF-8 encoded string instead of a Unicode object.

.. c: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 {
      const char *name;
      const unsigned char *code;
      int size;
      bool is_package;
  };

.. versionchanged:: 3.11 The new is_package field indicates whether the module is a package or not. This replaces setting the size field to a negative value.

.. c:var:: const struct _frozen* PyImport_FrozenModules

This pointer is initialized to point to an array of :c: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.

.. c:function:: int PyImport_AppendInittab(const char name, PyObject (*initfunc)(void))

Add a single module to the existing table of built-in modules. This is a convenience wrapper around :c:func: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 :c:func:Py_Initialize.

.. c:struct:: _inittab

Structure describing a single entry in the list of built-in modules. Programs which embed Python may use an array of these structures in conjunction with :c:func:PyImport_ExtendInittab to provide additional built-in modules. The structure consists of two members:

.. c:member:: const char *name

  The module name, as an ASCII encoded string.

.. c:member:: PyObject* (*initfunc)(void)

  Initialization function for a module built into the interpreter.

.. c:function:: 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 :c:member:~_inittab.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 must be called before :c:func:Py_Initialize.

If Python is initialized multiple times, :c:func:PyImport_AppendInittab or :c:func:PyImport_ExtendInittab must be called before each Python initialization.

.. c:var:: struct _inittab *PyImport_Inittab

The table of built-in modules used by Python initialization. Do not use this directly; use :c:func:PyImport_AppendInittab and :c:func:PyImport_ExtendInittab instead.

.. c:function:: PyObject* PyImport_ImportModuleAttr(PyObject *mod_name, PyObject *attr_name)

Import the module mod_name and get its attribute attr_name.

Names must be Python :class:str objects.

Helper function combining :c:func:PyImport_Import and :c:func:PyObject_GetAttr. For example, it can raise :exc:ImportError if the module is not found, and :exc:AttributeError if the attribute doesn't exist.

.. versionadded:: 3.14

.. c:function:: PyObject* PyImport_ImportModuleAttrString(const char *mod_name, const char *attr_name)

Similar to :c:func:PyImport_ImportModuleAttr, but names are UTF-8 encoded strings instead of Python :class:str objects.

.. versionadded:: 3.14

.. c:function:: PyImport_LazyImportsMode PyImport_GetLazyImportsMode()

Gets the current lazy imports mode.

.. versionadded:: 3.15

.. c:function:: PyObject* PyImport_GetLazyImportsFilter()

Return a :term:strong reference to the current lazy imports filter, or NULL if none exists. This function always succeeds.

.. versionadded:: 3.15

.. c:function:: int PyImport_SetLazyImportsMode(PyImport_LazyImportsMode mode)

Similar to :c:func:PyImport_ImportModuleAttr, but names are UTF-8 encoded strings instead of Python :class:str objects.

This function always returns 0.

.. versionadded:: 3.15

.. c:function:: int PyImport_SetLazyImportsFilter(PyObject *filter)

Sets the current lazy imports filter. The filter should be a callable that will receive (importing_module_name, imported_module_name, [fromlist]) when an import can potentially be lazy. The imported_module_name value is the resolved module name, so lazy from .spam import eggs passes package.spam. The callable must return True if the import should be lazy and False otherwise.

Return 0 on success and -1 with an exception set otherwise.

.. versionadded:: 3.15

.. c:type:: PyImport_LazyImportsMode

Enumeration of possible lazy import modes.

.. c:enumerator:: PyImport_LAZY_NORMAL

  Respect the ``lazy`` keyword in source code. This is the default mode.

.. c:enumerator:: PyImport_LAZY_ALL

  Make all imports lazy by default.

.. c:enumerator:: PyImport_LAZY_NONE

  Disable lazy imports entirely. Even explicit ``lazy`` statements become
  eager imports.

.. versionadded:: 3.15

.. c:function:: PyObject* PyImport_CreateModuleFromInitfunc(PyObject spec, PyObject (*initfunc)(void))

This function is a building block that enables embedders to implement the :py:meth:~importlib.abc.Loader.create_module step of custom static extension importers (e.g. of statically-linked extensions).

spec must be a :class:~importlib.machinery.ModuleSpec object.

initfunc must be an :ref:initialization function <extension-export-hook>, the same as for :c:func:PyImport_AppendInittab.

On success, create and return a module object. This module will not be initialized; call :c:func:PyModule_Exec to initialize it. (Custom importers should do this in their :py:meth:~importlib.abc.Loader.exec_module method.)

On error, return NULL with an exception set.

.. versionadded:: 3.15