diff options
Diffstat (limited to 'Doc/library/importlib.rst')
| -rw-r--r-- | Doc/library/importlib.rst | 241 |
1 files changed, 86 insertions, 155 deletions
diff --git a/Doc/library/importlib.rst b/Doc/library/importlib.rst index 9120671..e78a2ed 100644 --- a/Doc/library/importlib.rst +++ b/Doc/library/importlib.rst @@ -90,7 +90,7 @@ Functions Find the loader for a module, optionally within the specified *path*. If the module is in :attr:`sys.modules`, then ``sys.modules[name].__loader__`` is - returned (unless the loader would be ``None``, in which case + returned (unless the loader would be ``None`` or is not set, in which case :exc:`ValueError` is raised). Otherwise a search using :attr:`sys.meta_path` is done. ``None`` is returned if no loader is found. @@ -99,6 +99,12 @@ Functions will need to import all parent packages of the submodule and use the correct argument to *path*. + .. versionadded:: 3.3 + + .. versionchanged:: 3.4 + If ``__loader__`` is not set, raise :exc:`ValueError`, just like when the + attribute is set to ``None``. + .. function:: invalidate_caches() Invalidate the internal caches of finders stored at @@ -132,8 +138,6 @@ ABC hierarchy:: +-- ExecutionLoader --+ +-- FileLoader +-- SourceLoader - +-- PyLoader (deprecated) - +-- PyPycLoader (deprecated) .. class:: Finder @@ -149,6 +153,10 @@ ABC hierarchy:: module. Originally specified in :pep:`302`, this method was meant for use in :data:`sys.meta_path` and in the path-based import subsystem. + .. versionchanged:: 3.4 + Returns ``None`` when called instead of raising + :exc:`NotImplementedError`. + .. class:: MetaPathFinder @@ -165,12 +173,19 @@ ABC hierarchy:: will be the value of :attr:`__path__` from the parent package. If a loader cannot be found, ``None`` is returned. + .. versionchanged:: 3.4 + Returns ``None`` when called instead of raising + :exc:`NotImplementedError`. + .. method:: invalidate_caches() An optional method which, when called, should invalidate any internal cache used by the finder. Used by :func:`importlib.invalidate_caches` when invalidating the caches of all finders on :data:`sys.meta_path`. + .. versionchanged:: 3.4 + Returns ``None`` when called instead of ``NotImplemented``. + .. class:: PathEntryFinder @@ -178,7 +193,7 @@ ABC hierarchy:: it bears some similarities to :class:`MetaPathFinder`, ``PathEntryFinder`` is meant for use only within the path-based import subsystem provided by :class:`PathFinder`. This ABC is a subclass of :class:`Finder` for - compatibility. + compatibility reasons only. .. versionadded:: 3.3 @@ -190,9 +205,12 @@ ABC hierarchy:: package. The loader may be ``None`` while specifying ``portion`` to signify the contribution of the file system locations to a namespace package. An empty list can be used for ``portion`` to signify the loader - is not part of a package. If ``loader`` is ``None`` and ``portion`` is - the empty list then no loader or location for a namespace package were - found (i.e. failure to find anything for the module). + is not part of a namespace package. If ``loader`` is ``None`` and + ``portion`` is the empty list then no loader or location for a namespace + package were found (i.e. failure to find anything for the module). + + .. versionchanged:: 3.4 + Returns ``(None, [])`` instead of raising :exc:`NotImplementedError`. .. method:: find_module(fullname): @@ -245,20 +263,28 @@ ABC hierarchy:: - :attr:`__package__` The parent package for the module/package. If the module is top-level then it has a value of the empty string. The - :func:`importlib.util.set_package` decorator can handle the details - for :attr:`__package__`. + :func:`importlib.util.module_for_loader` decorator can handle the + details for :attr:`__package__`. - :attr:`__loader__` - The loader used to load the module. - (This is not set by the built-in import machinery, - but it should be set whenever a :term:`loader` is used.) + The loader used to load the module. The + :func:`importlib.util.module_for_loader` decorator can handle the + details for :attr:`__package__`. + + .. versionchanged:: 3.4 + Raise :exc:`ImportError` when called instead of + :exc:`NotImplementedError`. .. method:: module_repr(module) - An abstract method which when implemented calculates and returns the - given module's repr, as a string. + An optional method which when implemented calculates and returns the + given module's repr, as a string. The module type's default repr() will + use the result of this method as appropriate. - .. versionadded: 3.3 + .. versionadded:: 3.3 + + .. versionchanged:: 3.4 + Made optional instead of an abstractmethod. .. class:: ResourceLoader @@ -277,6 +303,9 @@ ABC hierarchy:: be found. The *path* is expected to be constructed using a module's :attr:`__file__` attribute or an item from a package's :attr:`__path__`. + .. versionchanged:: 3.4 + Raises :exc:`IOError` instead of :exc:`NotImplementedError`. + .. class:: InspectLoader @@ -293,6 +322,9 @@ ABC hierarchy:: .. index:: single: universal newlines; importlib.abc.InspectLoader.get_source method + .. versionchanged:: 3.4 + Raises :exc:`ImportError` instead of :exc:`NotImplementedError`. + .. method:: get_source(fullname) An abstract method to return the source of a module. It is returned as @@ -301,12 +333,18 @@ ABC hierarchy:: if no source is available (e.g. a built-in module). Raises :exc:`ImportError` if the loader cannot find the module specified. + .. versionchanged:: 3.4 + Raises :exc:`ImportError` instead of :exc:`NotImplementedError`. + .. method:: is_package(fullname) An abstract method to return a true value if the module is a package, a false value otherwise. :exc:`ImportError` is raised if the :term:`loader` cannot find the module. + .. versionchanged:: 3.4 + Raises :exc:`ImportError` instead of :exc:`NotImplementedError`. + .. class:: ExecutionLoader @@ -324,6 +362,9 @@ ABC hierarchy:: the source file, regardless of whether a bytecode was used to load the module. + .. versionchanged:: 3.4 + Raises :exc:`ImportError` instead of :exc:`NotImplementedError`. + .. class:: FileLoader(fullname, path) @@ -366,10 +407,12 @@ ABC hierarchy:: * :meth:`ResourceLoader.get_data` * :meth:`ExecutionLoader.get_filename` Should only return the path to the source file; sourceless - loading is not supported. + loading is not supported (see :class:`SourcelessLoader` if that + functionality is required) The abstract methods defined by this class are to add optional bytecode - file support. Not implementing these optional methods causes the loader to + file support. Not implementing these optional methods (or causing them to + raise :exc:`NotImplementedError`) causes the loader to only work with source code. Implementing the methods allows the loader to work with source *and* bytecode files; it does not allow for *sourceless* loading where only bytecode is provided. Bytecode files are an @@ -386,10 +429,13 @@ ABC hierarchy:: - ``'size'`` (optional): the size in bytes of the source code. Any other keys in the dictionary are ignored, to allow for future - extensions. + extensions. If the path cannot be handled, :exc:`IOError` is raised. .. versionadded:: 3.3 + .. versionchanged:: 3.4 + Raise :exc:`IOError` instead of :exc:`NotImplementedError`. + .. method:: path_mtime(path) Optional abstract method which returns the modification time for the @@ -398,7 +444,10 @@ ABC hierarchy:: .. deprecated:: 3.3 This method is deprecated in favour of :meth:`path_stats`. You don't have to implement it, but it is still available for compatibility - purposes. + purposes. Raise :exc:`IOError` if the path cannot be handled. + + .. versionchanged:: 3.4 + Raise :exc:`IOError` instead of :exc:`NotImplementedError`. .. method:: set_data(path, data) @@ -409,6 +458,20 @@ ABC hierarchy:: When writing to the path fails because the path is read-only (:attr:`errno.EACCES`), do not propagate the exception. + .. versionchanged:: 3.4 + No longer raises :exc:`NotImplementedError` when called. + + .. method:: source_to_code(data, path) + + Create a code object from Python source. + + The *data* argument can be whatever the :func:`compile` function + supports (i.e. string or bytes). The *path* argument should be + the "path" to where the source code originated from, which can be an + abstract concept (e.g. location in a zip file). + + .. versionadded:: 3.4 + .. method:: get_code(fullname) Concrete implementation of :meth:`InspectLoader.get_code`. @@ -430,142 +493,6 @@ ABC hierarchy:: itself does not end in ``__init__``. -.. class:: PyLoader - - An abstract base class inheriting from - :class:`ExecutionLoader` and - :class:`ResourceLoader` designed to ease the loading of - Python source modules (bytecode is not handled; see - :class:`SourceLoader` for a source/bytecode ABC). A subclass - implementing this ABC will only need to worry about exposing how the source - code is stored; all other details for loading Python source code will be - handled by the concrete implementations of key methods. - - .. deprecated:: 3.2 - This class has been deprecated in favor of :class:`SourceLoader` and is - slated for removal in Python 3.4. See below for how to create a - subclass that is compatible with Python 3.1 onwards. - - If compatibility with Python 3.1 is required, then use the following idiom - to implement a subclass that will work with Python 3.1 onwards (make sure - to implement :meth:`ExecutionLoader.get_filename`):: - - try: - from importlib.abc import SourceLoader - except ImportError: - from importlib.abc import PyLoader as SourceLoader - - - class CustomLoader(SourceLoader): - def get_filename(self, fullname): - """Return the path to the source file.""" - # Implement ... - - def source_path(self, fullname): - """Implement source_path in terms of get_filename.""" - try: - return self.get_filename(fullname) - except ImportError: - return None - - def is_package(self, fullname): - """Implement is_package by looking for an __init__ file - name as returned by get_filename.""" - filename = os.path.basename(self.get_filename(fullname)) - return os.path.splitext(filename)[0] == '__init__' - - - .. method:: source_path(fullname) - - An abstract method that returns the path to the source code for a - module. Should return ``None`` if there is no source code. - Raises :exc:`ImportError` if the loader knows it cannot handle the - module. - - .. method:: get_filename(fullname) - - A concrete implementation of - :meth:`importlib.abc.ExecutionLoader.get_filename` that - relies on :meth:`source_path`. If :meth:`source_path` returns - ``None``, then :exc:`ImportError` is raised. - - .. method:: load_module(fullname) - - A concrete implementation of :meth:`importlib.abc.Loader.load_module` - that loads Python source code. All needed information comes from the - abstract methods required by this ABC. The only pertinent assumption - made by this method is that when loading a package - :attr:`__path__` is set to ``[os.path.dirname(__file__)]``. - - .. method:: get_code(fullname) - - A concrete implementation of - :meth:`importlib.abc.InspectLoader.get_code` that creates code objects - from Python source code, by requesting the source code (using - :meth:`source_path` and :meth:`get_data`) and compiling it with the - built-in :func:`compile` function. - - .. method:: get_source(fullname) - - A concrete implementation of - :meth:`importlib.abc.InspectLoader.get_source`. Uses - :meth:`importlib.abc.ResourceLoader.get_data` and :meth:`source_path` - to get the source code. It tries to guess the source encoding using - :func:`tokenize.detect_encoding`. - - -.. class:: PyPycLoader - - An abstract base class inheriting from :class:`PyLoader`. - This ABC is meant to help in creating loaders that support both Python - source and bytecode. - - .. deprecated:: 3.2 - This class has been deprecated in favor of :class:`SourceLoader` and to - properly support :pep:`3147`. If compatibility is required with - Python 3.1, implement both :class:`SourceLoader` and :class:`PyLoader`; - instructions on how to do so are included in the documentation for - :class:`PyLoader`. Do note that this solution will not support - sourceless/bytecode-only loading; only source *and* bytecode loading. - - .. versionchanged:: 3.3 - Updated to parse (but not use) the new source size field in bytecode - files when reading and to write out the field properly when writing. - - .. method:: source_mtime(fullname) - - An abstract method which returns the modification time for the source - code of the specified module. The modification time should be an - integer. If there is no source code, return ``None``. If the - module cannot be found then :exc:`ImportError` is raised. - - .. method:: bytecode_path(fullname) - - An abstract method which returns the path to the bytecode for the - specified module, if it exists. It returns ``None`` - if no bytecode exists (yet). - Raises :exc:`ImportError` if the loader knows it cannot handle the - module. - - .. method:: get_filename(fullname) - - A concrete implementation of - :meth:`ExecutionLoader.get_filename` that relies on - :meth:`PyLoader.source_path` and :meth:`bytecode_path`. - If :meth:`source_path` returns a path, then that value is returned. - Else if :meth:`bytecode_path` returns a path, that path will be - returned. If a path is not available from both methods, - :exc:`ImportError` is raised. - - .. method:: write_bytecode(fullname, bytecode) - - An abstract method which has the loader write *bytecode* for future - use. If the bytecode is written, return ``True``. Return - ``False`` if the bytecode could not be written. This method - should not be called if :data:`sys.dont_write_bytecode` is true. - The *bytecode* argument should be a bytes string or bytes array. - - :mod:`importlib.machinery` -- Importers and path hooks ------------------------------------------------------ @@ -899,6 +826,10 @@ an :term:`importer`. It is recommended that :func:`module_for_loader` be used over this decorator as it subsumes this functionality. + .. versionchanged:: 3.4 + Set ``__loader__`` if set to ``None`` as well if the attribute does not + exist. + .. decorator:: set_package |