.. 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`)::

.. 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.