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-rw-r--r--Doc/library/importlib.rst496
1 files changed, 302 insertions, 194 deletions
diff --git a/Doc/library/importlib.rst b/Doc/library/importlib.rst
index efd027b..f918bfb 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
@@ -109,6 +115,74 @@ Functions
.. versionadded:: 3.3
+.. function:: reload(module)
+
+ Reload a previously imported *module*. The argument must be a module object,
+ so it must have been successfully imported before. This is useful if you
+ have edited the module source file using an external editor and want to try
+ out the new version without leaving the Python interpreter. The return value
+ is the module object (which can be different if re-importing causes a
+ different object to be placed in :data:`sys.modules`).
+
+ When :func:`reload` is executed:
+
+ * Python modules' code is recompiled and the module-level code re-executed,
+ defining a new set of objects which are bound to names in the module's
+ dictionary by reusing the :term:`loader` which originally loaded the
+ module. The ``init`` function of extension modules is not called a second
+ time.
+
+ * As with all other objects in Python the old objects are only reclaimed
+ after their reference counts drop to zero.
+
+ * The names in the module namespace are updated to point to any new or
+ changed objects.
+
+ * Other references to the old objects (such as names external to the module) are
+ not rebound to refer to the new objects and must be updated in each namespace
+ where they occur if that is desired.
+
+ There are a number of other caveats:
+
+ If a module is syntactically correct but its initialization fails, the first
+ :keyword:`import` statement for it does not bind its name locally, but does
+ store a (partially initialized) module object in ``sys.modules``. To reload
+ the module you must first :keyword:`import` it again (this will bind the name
+ to the partially initialized module object) before you can :func:`reload` it.
+
+ When a module is reloaded, its dictionary (containing the module's global
+ variables) is retained. Redefinitions of names will override the old
+ definitions, so this is generally not a problem. If the new version of a
+ module does not define a name that was defined by the old version, the old
+ definition remains. This feature can be used to the module's advantage if it
+ maintains a global table or cache of objects --- with a :keyword:`try`
+ statement it can test for the table's presence and skip its initialization if
+ desired::
+
+ try:
+ cache
+ except NameError:
+ cache = {}
+
+ It is legal though generally not very useful to reload built-in or
+ dynamically loaded modules (this is not true for e.g. :mod:`sys`,
+ :mod:`__main__`, :mod:`builtins` and other key modules where reloading is
+ frowned upon). In many cases, however, extension modules are not designed to
+ be initialized more than once, and may fail in arbitrary ways when reloaded.
+
+ If a module imports objects from another module using :keyword:`from` ...
+ :keyword:`import` ..., calling :func:`reload` for the other module does not
+ redefine the objects imported from it --- one way around this is to
+ re-execute the :keyword:`from` statement, another is to use :keyword:`import`
+ and qualified names (*module.name*) instead.
+
+ If a module instantiates instances of a class, reloading the module that
+ defines the class does not affect the method definitions of the instances ---
+ they continue to use the old class definition. The same is true for derived
+ classes.
+
+ .. versionadded:: 3.4
+
:mod:`importlib.abc` -- Abstract base classes related to import
---------------------------------------------------------------
@@ -132,8 +206,6 @@ ABC hierarchy::
+-- ExecutionLoader --+
+-- FileLoader
+-- SourceLoader
- +-- PyLoader (deprecated)
- +-- PyPycLoader (deprecated)
.. class:: Finder
@@ -149,6 +221,10 @@ 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 +241,19 @@ 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 +261,7 @@ 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 +273,12 @@ 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)
@@ -224,12 +310,11 @@ ABC hierarchy::
from the import. If the loader inserted a module and the load fails, it
must be removed by the loader from :data:`sys.modules`; modules already
in :data:`sys.modules` before the loader began execution should be left
- alone. The :func:`importlib.util.module_for_loader` decorator handles
- all of these details.
+ alone (see :func:`importlib.util.module_to_load`).
The loader should set several attributes on the module.
(Note that some of these attributes can change when a module is
- reloaded.)
+ reloaded; see :meth:`init_module_attrs`):
- :attr:`__name__`
The name of the module.
@@ -249,20 +334,39 @@ 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.
+
+ .. method:: init_module_attrs(module)
+
+ Set the :attr:`__loader__` attribute on the module.
+
+ Subclasses overriding this method should set whatever appropriate
+ attributes it can, getting the module's name from :attr:`__name__` when
+ needed. All values should also be overridden so that reloading works as
+ expected.
+
+ .. versionadded:: 3.4
.. class:: ResourceLoader
@@ -281,6 +385,9 @@ 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
@@ -289,14 +396,21 @@ ABC hierarchy::
.. method:: get_code(fullname)
- An abstract method to return the :class:`code` object for a module.
- ``None`` is returned if the module does not have a code object
+ Return the code object for a module.
+ ``None`` should be returned if the module does not have a code object
(e.g. built-in module). :exc:`ImportError` is raised if loader cannot
find the requested module.
+ .. note::
+ While the method has a default implementation, it is suggested that
+ it be overridden if possible for performance.
+
.. index::
single: universal newlines; importlib.abc.InspectLoader.get_source method
+ .. versionchanged:: 3.4
+ No longer abstract and a concrete implementation is provided.
+
.. method:: get_source(fullname)
An abstract method to return the source of a module. It is returned as
@@ -305,12 +419,41 @@ 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`.
+
+ .. method:: source_to_code(data, path='<string>')
+
+ 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:: init_module_attrs(module)
+
+ Set the :attr:`__package__` attribute and :attr:`__path__` attribute to
+ the empty list if appropriate along with what
+ :meth:`importlib.abc.Loader.init_module_attrs` sets.
+
+ .. versionadded:: 3.4
+
+ .. method:: load_module(fullname)
+
+ Implementation of :meth:`Loader.load_module`.
+
.. class:: ExecutionLoader
@@ -328,6 +471,18 @@ 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`.
+
+ .. method:: init_module_attrs(module)
+
+ Set :attr:`__file__` and if initializing a package then set
+ :attr:`__path__` to ``[os.path.dirname(__file__)]`` along with
+ all attributes set by
+ :meth:`importlib.abc.InspectLoader.init_module_attrs`.
+
+ .. versionadded:: 3.4
+
.. class:: FileLoader(fullname, path)
@@ -358,7 +513,7 @@ ABC hierarchy::
.. method:: get_data(path)
- Returns the open, binary file for *path*.
+ Reads *path* as a binary file and returns the bytes from it.
.. class:: SourceLoader
@@ -373,7 +528,8 @@ ABC hierarchy::
loading is not supported.
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
@@ -390,10 +546,13 @@ 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
@@ -402,7 +561,10 @@ 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)
@@ -414,6 +576,9 @@ ABC hierarchy::
(:attr:`errno.EACCES`/:exc:`PermissionError`), do not propagate the
exception.
+ .. versionchanged:: 3.4
+ No longer raises :exc:`NotImplementedError` when called.
+
.. method:: get_code(fullname)
Concrete implementation of :meth:`InspectLoader.get_code`.
@@ -434,141 +599,13 @@ ABC hierarchy::
``__init__`` when the file extension is removed **and** the module name
itself does not end in ``__init__``.
+ .. method:: init_module_attr(module)
-.. 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`)::
+ Set :attr:`__cached__` using :func:`imp.cache_from_source`. Other
+ attributes set by
+ :meth:`importlib.abc.ExecutionLoader.init_module_attrs`.
- 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.
+ .. versionadded:: 3.4
:mod:`importlib.machinery` -- Importers and path hooks
@@ -686,6 +723,10 @@ find and load modules.
Calls :meth:`importlib.abc.PathEntryFinder.invalidate_caches` on all
finders stored in :attr:`sys.path_importer_cache`.
+ .. versionchanged:: 3.4
+ Calls objects in :data:`sys.path_hooks` with the current working directory
+ for ``''`` (i.e. the empty string).
+
.. class:: FileFinder(path, \*loader_details)
@@ -712,6 +753,9 @@ find and load modules.
.. versionadded:: 3.3
+ .. versionchanged:: 3.4
+ The empty string is no longer special-cased to be changed into ``'.'``.
+
.. attribute:: path
The path the finder will search in.
@@ -800,7 +844,7 @@ find and load modules.
.. class:: ExtensionFileLoader(fullname, path)
- A concrete implementation of :class:`importlib.abc.InspectLoader` for
+ A concrete implementation of :class:`importlib.abc.ExecutionLoader` for
extension modules.
The *fullname* argument specifies the name of the module the loader is to
@@ -834,6 +878,12 @@ find and load modules.
Returns ``None`` as extension modules do not have source code.
+ .. method:: get_filename(fullname)
+
+ Returns :attr:`path`.
+
+ .. versionadded:: 3.4
+
:mod:`importlib.util` -- Utility code for importers
---------------------------------------------------
@@ -844,6 +894,51 @@ find and load modules.
This module contains the various objects that help in the construction of
an :term:`importer`.
+.. attribute:: MAGIC_NUMBER
+
+ The bytes which represent the bytecode version number. If you need help with
+ loading/writing bytecode then consider :class:`importlib.abc.SourceLoader`.
+
+ .. versionadded:: 3.4
+
+.. function:: cache_from_source(path, debug_override=None)
+
+ Return the :pep:`3147` path to the byte-compiled file associated with the
+ source *path*. For example, if *path* is ``/foo/bar/baz.py`` the return
+ value would be ``/foo/bar/__pycache__/baz.cpython-32.pyc`` for Python 3.2.
+ The ``cpython-32`` string comes from the current magic tag (see
+ :func:`get_tag`; if :attr:`sys.implementation.cache_tag` is not defined then
+ :exc:`NotImplementedError` will be raised). The returned path will end in
+ ``.pyc`` when ``__debug__`` is True or ``.pyo`` for an optimized Python
+ (i.e. ``__debug__`` is False). By passing in True or False for
+ *debug_override* you can override the system's value for ``__debug__`` for
+ extension selection.
+
+ *path* need not exist.
+
+ .. versionadded:: 3.4
+
+
+.. function:: source_from_cache(path)
+
+ Given the *path* to a :pep:`3147` file name, return the associated source code
+ file path. For example, if *path* is
+ ``/foo/bar/__pycache__/baz.cpython-32.pyc`` the returned path would be
+ ``/foo/bar/baz.py``. *path* need not exist, however if it does not conform
+ to :pep:`3147` format, a ``ValueError`` is raised. If
+ :attr:`sys.implementation.cache_tag` is not defined,
+ :exc:`NotImplementedError` is raised.
+
+ .. versionadded:: 3.4
+
+.. function:: decode_source(source_bytes)
+
+ Decode the given bytes representing source code and return it as a string
+ with universal newlines (as required by
+ :meth:`importlib.abc.InspectLoader.get_source`).
+
+ .. versionadded:: 3.4
+
.. function:: resolve_name(name, package)
Resolve a relative module name to an absolute one.
@@ -860,9 +955,23 @@ an :term:`importer`.
.. versionadded:: 3.3
+.. function:: module_to_load(name, *, reset_name=True)
+
+ Returns a :term:`context manager` which provides the module to load. The
+ module will either come from :attr:`sys.modules` in the case of reloading or
+ a fresh module if loading a new module. Proper cleanup of
+ :attr:`sys.modules` occurs if the module was new and an exception was
+ raised.
+
+ If **reset_name** is true and the module requested is being reloaded then
+ the module's :attr:`__name__` attribute will
+ be reset to **name**, else it will be left untouched.
+
+ .. versionadded:: 3.4
+
.. decorator:: module_for_loader
- A :term:`decorator` for a :term:`loader` method,
+ A :term:`decorator` for :meth:`importlib.abc.Loader.load_module`
to handle selecting the proper
module object to load with. The decorated method is expected to have a call
signature taking two positional arguments
@@ -873,55 +982,54 @@ an :term:`importer`.
The decorated method will take in the **name** of the module to be loaded
as expected for a :term:`loader`. If the module is not found in
- :data:`sys.modules` then a new one is constructed with its
- :attr:`__name__` attribute set to **name**, :attr:`__loader__` set to
- **self**, and :attr:`__package__` set if
- :meth:`importlib.abc.InspectLoader.is_package` is defined for **self** and
- does not raise :exc:`ImportError` for **name**. If a new module is not
- needed then the module found in :data:`sys.modules` will be passed into the
- method.
+ :data:`sys.modules` then a new one is constructed. Regardless of where the
+ module came from, :attr:`__loader__` set to **self** and :attr:`__package__`
+ is set based on what :meth:`importlib.abc.InspectLoader.is_package` returns
+ (if available). These attributes are set unconditionally to support
+ reloading.
If an exception is raised by the decorated method and a module was added to
- :data:`sys.modules` it will be removed to prevent a partially initialized
- module from being in left in :data:`sys.modules`. If the module was already
- in :data:`sys.modules` then it is left alone.
-
- Use of this decorator handles all the details of which module object a
- loader should initialize as specified by :pep:`302` as best as possible.
+ :data:`sys.modules`, then the module will be removed to prevent a partially
+ initialized module from being in left in :data:`sys.modules`. If the module
+ was already in :data:`sys.modules` then it is left alone.
.. versionchanged:: 3.3
:attr:`__loader__` and :attr:`__package__` are automatically set
(when possible).
+ .. versionchanged:: 3.4
+ Set :attr:`__name__`, :attr:`__loader__` :attr:`__package__`
+ unconditionally to support reloading.
+
+ .. deprecated:: 3.4
+ For the benefit of :term:`loader` subclasses, please use
+ :func:`module_to_load` and
+ :meth:`importlib.abc.Loader.init_module_attrs` instead.
+
.. decorator:: set_loader
- A :term:`decorator` for a :term:`loader` method,
- to set the :attr:`__loader__`
- attribute on loaded modules. If the attribute is already set the decorator
- does nothing. It is assumed that the first positional argument to the
- wrapped method (i.e. ``self``) is what :attr:`__loader__` should be set to.
+ A :term:`decorator` for :meth:`importlib.abc.Loader.load_module`
+ to set the :attr:`__loader__`
+ attribute on the returned module. If the attribute is already set the
+ decorator does nothing. It is assumed that the first positional argument to
+ the wrapped method (i.e. ``self``) is what :attr:`__loader__` should be set
+ to.
.. note::
+ As this decorator sets :attr:`__loader__` after loading the module, it is
+ recommended to use :meth:`importlib.abc.Loader.init_module_attrs` instead
+ when appropriate.
- 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 if the attribute does not
+ exist.
.. decorator:: set_package
- A :term:`decorator` for a :term:`loader` to set the :attr:`__package__`
- attribute on the module returned by the loader. If :attr:`__package__` is
- set and has a value other than ``None`` it will not be changed.
- Note that the module returned by the loader is what has the attribute
- set on and not the module found in :data:`sys.modules`.
-
- Reliance on this decorator is discouraged when it is possible to set
- :attr:`__package__` before importing. By
- setting it beforehand the code for the module is executed with the
- attribute set and thus can be used by global level code during
- initialization.
+ A :term:`decorator` for :meth:`importlib.abc.Loader.load_module` to set the :attr:`__package__` attribute on the returned module. If :attr:`__package__`
+ is set and has a value other than ``None`` it will not be changed.
.. note::
-
- It is recommended that :func:`module_for_loader` be used over this
- decorator as it subsumes this functionality.
+ As this decorator sets :attr:`__package__` after loading the module, it is
+ recommended to use :meth:`importlib.abc.Loader.init_module_attrs` instead
+ when appropriate.