diff -r ffa851df0825 -r 2fb8b9db1c86 symbian-qemu-0.9.1-12/python-2.6.1/Doc/distutils/extending.rst --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/symbian-qemu-0.9.1-12/python-2.6.1/Doc/distutils/extending.rst Fri Jul 31 15:01:17 2009 +0100 @@ -0,0 +1,96 @@ +.. _extending-distutils: + +******************* +Extending Distutils +******************* + +Distutils can be extended in various ways. Most extensions take the form of new +commands or replacements for existing commands. New commands may be written to +support new types of platform-specific packaging, for example, while +replacements for existing commands may be made to modify details of how the +command operates on a package. + +Most extensions of the distutils are made within :file:`setup.py` scripts that +want to modify existing commands; many simply add a few file extensions that +should be copied into packages in addition to :file:`.py` files as a +convenience. + +Most distutils command implementations are subclasses of the :class:`Command` +class from :mod:`distutils.cmd`. New commands may directly inherit from +:class:`Command`, while replacements often derive from :class:`Command` +indirectly, directly subclassing the command they are replacing. Commands are +required to derive from :class:`Command`. + +.. % \section{Extending existing commands} +.. % \label{extend-existing} + +.. % \section{Writing new commands} +.. % \label{new-commands} +.. % \XXX{Would an uninstall command be a good example here?} + + +Integrating new commands +======================== + +There are different ways to integrate new command implementations into +distutils. The most difficult is to lobby for the inclusion of the new features +in distutils itself, and wait for (and require) a version of Python that +provides that support. This is really hard for many reasons. + +The most common, and possibly the most reasonable for most needs, is to include +the new implementations with your :file:`setup.py` script, and cause the +:func:`distutils.core.setup` function use them:: + + from distutils.command.build_py import build_py as _build_py + from distutils.core import setup + + class build_py(_build_py): + """Specialized Python source builder.""" + + # implement whatever needs to be different... + + setup(cmdclass={'build_py': build_py}, + ...) + +This approach is most valuable if the new implementations must be used to use a +particular package, as everyone interested in the package will need to have the +new command implementation. + +Beginning with Python 2.4, a third option is available, intended to allow new +commands to be added which can support existing :file:`setup.py` scripts without +requiring modifications to the Python installation. This is expected to allow +third-party extensions to provide support for additional packaging systems, but +the commands can be used for anything distutils commands can be used for. A new +configuration option, :option:`command_packages` (command-line option +:option:`--command-packages`), can be used to specify additional packages to be +searched for modules implementing commands. Like all distutils options, this +can be specified on the command line or in a configuration file. This option +can only be set in the ``[global]`` section of a configuration file, or before +any commands on the command line. If set in a configuration file, it can be +overridden from the command line; setting it to an empty string on the command +line causes the default to be used. This should never be set in a configuration +file provided with a package. + +This new option can be used to add any number of packages to the list of +packages searched for command implementations; multiple package names should be +separated by commas. When not specified, the search is only performed in the +:mod:`distutils.command` package. When :file:`setup.py` is run with the option +:option:`--command-packages` :option:`distcmds,buildcmds`, however, the packages +:mod:`distutils.command`, :mod:`distcmds`, and :mod:`buildcmds` will be searched +in that order. New commands are expected to be implemented in modules of the +same name as the command by classes sharing the same name. Given the example +command line option above, the command :command:`bdist_openpkg` could be +implemented by the class :class:`distcmds.bdist_openpkg.bdist_openpkg` or +:class:`buildcmds.bdist_openpkg.bdist_openpkg`. + + +Adding new distribution types +============================= + +Commands that create distributions (files in the :file:`dist/` directory) need +to add ``(command, filename)`` pairs to ``self.distribution.dist_files`` so that +:command:`upload` can upload it to PyPI. The *filename* in the pair contains no +path information, only the name of the file itself. In dry-run mode, pairs +should still be added to represent what would have been created. + +