Introduction
==============
.. image:: https://travis-ci.org/embray/d2to1.png?branch=master
   :alt: travis build status
   :target: https://travis-ci.org/embray/d2to1

d2to1 (the 'd' is for 'distutils') allows using distutils2-like setup.cfg files
for a package's metadata with a distribute/setuptools setup.py script.  It
works by providing a distutils2-formatted setup.cfg file containing all of a
package's metadata, and a very minimal setup.py which will slurp its arguments
from the setup.cfg.

Note: distutils2 has been merged into the CPython standard library, where it is
now known as 'packaging'.  This project was started before that change was
finalized.  So all references to distutils2 should also be assumed to refer to
packaging.

Rationale
===========
I'm currently in the progress of redoing the packaging of a sizeable number of
projects.  I wanted to use distutils2-like setup.cfg files for all these
projects, as they will hopefully be the future, and I much prefer them overall
to using an executable setup.py.  So forward-support for distutils2 is
appealing both as future-proofing, and simply the aesthetics of using a flat text file to describe a project's metadata.

However, I did not want any of these projects to require distutils2 for
installation yet--it is too unstable, and not widely installed.  So projects
should still be installable using the familiar `./setup.py install`, for
example.  Furthermore, not all use cases required by some of the packages I
support are fully supported by distutils2 yet.  Hopefully they will be
eventually, either through the distutils2 core or through extensions.  But in
the meantime d2to1 will try to keep up with the state of the art and "best
practices" for distutils2 distributions, while adding support in areas that
it's lacking.

Usage
=======
d2to1 requires a distribution to use distribute or setuptools.  Your
distribution must include a distutils2-like setup.cfg file, and a minimal
setup.py script.  For details on writing the setup.cfg, see the `distutils2
documentation`_.  A simple sample can be found in d2to1's own setup.cfg (it
uses its own machinery to install itself)::

    [metadata]
    name = d2to1
    version = 0.2.12
    author = Erik M. Bray
    author-email = embray@stsci.edu
    summary = Allows using distutils2-like setup.cfg files for a package's metadata with a distribute/setuptools setup.py
    description-file =
        README.rst
        CHANGES.rst
    home-page = http://pypi.python.org/pypi/d2to1
    requires-dist = setuptools
    classifier = 
        Development Status :: 5 - Production/Stable
        Environment :: Plugins
        Framework :: Setuptools Plugin
        Intended Audience :: Developers
        License :: OSI Approved :: BSD License
        Operating System :: OS Independent
        Programming Language :: Python
        Programming Language :: Python :: 3
        Topic :: Software Development :: Build Tools
        Topic :: Software Development :: Libraries :: Python Modules
        Topic :: System :: Archiving :: Packaging

    [files]
    packages =
        d2to1
        d2to1.extern
    extra_files =
        CHANGES.rst
        LICENSE
        ez_setup.py

    [backwards_compat]
    zip-safe = False
    tests-require = nose

    [entry_points]
    distutils.setup_keywords = 
        d2to1 = d2to1.core:d2to1
    zest.releaser.prereleaser.middle = 
        d2_version = d2to1.zestreleaser:prereleaser_middle
    zest.releaser.postreleaser.middle = 
        d2_version = d2to1.zestreleaser:postreleaser_middle

The minimal setup.py should look something like this::

 #!/usr/bin/env python

 try:
     from setuptools import setup
 except ImportError:
     from distribute_setup import use_setuptools
     use_setuptools()
     from setuptools import setup

 setup(
     setup_requires=['d2to1'],
     d2to1=True
 )

Note that it's important to specify d2to1=True or else the d2to1 functionality
will not be enabled.  It is also possible to set d2to1='some_file.cfg' to
specify the (relative) path of the setup.cfg file to use.  But in general this
functionality should not be necessary.

It should also work fine if additional arguments are passed to `setup()`,
but it should be noted that they will be clobbered by any options in the
setup.cfg file.

Caveats
=======
- The requires-dist option in setup.cfg is implemented through the
  distribute/setuptools install_requires option, rather than the broken
  "requires" keyword in normal distutils.
- Not all features of distutils2 are supported yet.  If something doesn't seem
  to be working, it's probably not implemented yet.
- Does not support distutils2 resources, and probably won't since it relies
  heavily on the sysconfig module only available in Python 3.2 and up.  This is
  one area in which d2to1 should really be seen as a transitional tool.  I
  don't really want to include a backport like distutils2 does.  In the
  meantime, package_data and data_files may still be used under the [files]
  section of setup.cfg.

.. _distutils2 documentation: http://alexis.notmyidea.org/distutils2/setupcfg.html

Changes
=========

0.2.12 (2015-07-16)
-------------------

- Fixed a corner case where depending on the order of events when installing
  multiple packages (i.e. when installing packages with dependencies, some
  of which might also use d2to1) we would end up calling the incorrect
  Distribution class (the patched version from setuptools, where d2to1
  needs to get to the unpatched version from distutils for some cases).

- Upgraded bundled copy of the ``six`` module to the current version
  (1.9.0).  This fixes incompatibility between d2to1 and other packages
  that import different versions of ``six`` during their setup (the older
  version of ``six`` had a habit of fighting with other ``six`` instances
  over ``sys.modules``, which is fixed in newer versions).

- Upgraded to latest ``ez_setup.py`` so that the most up to date version
  of setuptools will be correctly bootstrapped in the rare cases that it
  is needed.

- Included some miscellaneous hacks to keep d2to1 working, nominally, with
  Python 2.5 despite the broad move away from Python 2.5 support in the
  Python community.  The d2to1 v0.2.x releases will be the last to continue
  Python 2.5 support, given that testing it has become more difficult (and
  the overhead is probably no longer worth it).


0.2.11 (2013-08-29)
-------------------

- Replaced ``distribute_setup.py`` with ``ez_setup.py`` in order to bootstrap
  with modern setuptools when necessary.

- Fixed a couple minor Python 3-specific issues. In particular the
  ``data_files`` option could be passed to ``setup()`` as a ``dict_items``
  object instead of a ``list`` which is what would normally be expected.

- Added a tox.ini (frankly I thought there already was one).


0.2.10 (2013-04-10)
-------------------

- Added support for the ``setup-requires-dist`` option in the ``[metadata]``
  section of setup.cfg.  This is analogous to the Setup-Requires-Dist metadata
  field supported by PEP-426 and uses the ``setup_requires`` argument to
  setuptools' ``setup()`` to implement it.

- Added support for the ``dependency_links`` and ``include_package_data``
  arguments to setuptools' ``setup()`` in the ``[backwards_compat]`` section of
  setup.cfg.

- When a setup_hook calls sys.exit() don't show a traceback for the
  SystemExit exception.

- Fixed a bug in the exception formatting when exceptions occur in setup.cfg
  handling.


0.2.9 (2013-03-05)
------------------

- Fixed a bug in the extra-files supported added in 0.2.8.  Makes sure that
  monkey-patches can't be installed more than once and that the log
  reference is properly encapsulated.


0.2.8 (2013-03-05)
------------------

- Improved handling of packages where the packages_root option is set. That is,
  the Python package is not directly in the root of the source tree, but is in
  some sub-directory.  Now the packages_root directory is prepended to
  sys.path while processing the setup.cfg and running setup hooks.

- Added support for the Keywords metadata field via the keywords option in the
  ``[metadata]`` section of setup.cfg.

- Fixed a missing import that caused a misleading exception when setup.cfg is
  missing.

- Upgraded the shipped distribute_setup.py to the latest for distribute 0.6.28

- Added a few basic functional tests, along with an infrastructure to add more
  as needed.  They can be run with nose and possibly with py.test though the
  latter hasn't been tested.

- Improved hook imports to work better with namespace packages.

- Added support for the extra_files option of the ``[files]`` section in
  setup.cfg.  This was a feature from distutils2 that provided an alternative
  to MANIFEST.in for including additional files in source distributions (it
  does not yet support wildcard patterns but maybe it should?)

- Added support for the tests_require setup argument from setuptools via
  the [backwards_compat] section in setup.cfg.

- Supports Python 3 natively without 2to3.  This makes Python 3 testing of
  d2to1 easier to support.


0.2.7 (2012-02-20)
------------------

- If no extension modules or entry points are defined in the setup.cfg, don't
  clobber any extension modules/entry points that may be defined in setup.py.


0.2.6 (2012-02-17)
------------------

- Added support for setuptools entry points in an ``[entry_points]`` section of
  setup.cfg--this is just for backwards-compatibility purposes, as
  packaging/distutils2 does not yet have a standard replacement for the entry
  points system.

- Added a [backwards_compat] section for setup.cfg for other options that are
  supported by setuptools/distribute, but that aren't part of the distutils2
  standard.  So far the only options supported here are zip_safe and use_2to3.
  (Note: packaging does support a use-2to3 option to the build command, but if
  we tried to use that, distutils would not recognize it as a valid build
  option.)

- Added support for the new (and presumably final) extension section format
  used by packaging.  In this format, extensions should be specified in config
  sections of the format ``[extension: ext_mod_name]``, where any whitespace is
  optional.  The old format used an ``=`` instead of ``:`` and is still
  supported, but should be considered deprecated.

- Added support for the new syntax used by packaging for the package_data
  option (which is deprecated in packaging in favor of the resources system,
  but still supported).  The new syntax is like::

      package_data =
          packagename = pattern1 pattern2 pattern3
          packagename.subpack = 
              pattern1
              pattern2
              pattern3

  That is, after ``package_data =``, give the name of a package, followed by
  an ``=``, followed by any number of whitespace separated wildcard patterns (or
  actual filenames relative to the package).  Under this scheme, whitespace is
  not allowed in the patterns themselves.


0.2.5 (2011-07-21)
------------------

- Made the call to pkg_resources.get_distribution() to set __version__ more
  robust, so that it doesn't fail on, for example, VersionConflict errors


0.2.4 (2011-07-05)
------------------

- Fixed some bugs with installation on Python 3


0.2.3 (2011-06-23)
------------------

- Renamed 'setup_hook' to 'setup_hooks' as is now the case in the packaging
  module.  Added support for multiple setup_hooks


0.2.2 (2011-06-15)
------------------

- Fixed a bug in DefaultGetDict where it didn't actually save the returned
  default in the dictionary--so any command options would get lost
- Fixed a KeyError when the distribution does not have any custom commands
  specified


0.2.1 (2011-06-15)
------------------

- Reimplemented command hooks without monkey-patching and more reliably in
  general (though it's still a flaming hack).  The previous monkey patch-based
  solution would break if d2to1 were entered multiple times, which could happen
  in some scenarios


0.2.0 (2011-06-14)
------------------

- Version bump to start using micro-version numbers for bug fixes only, now
  that the my primary feature goals are complete


0.1.5 (2011-06-02)
------------------

- Adds support for the data_files option under [files].  Though this is
  considered deprecated and may go away at some point, it can be useful in the
  absence of resources support
- Adds support for command pre/post-hooks.  Warning: this monkey-patches
  distutils.dist.Distribution a little bit... :(
- Adds (slightly naive) support for PEP 345-style version specifiers in
  requires-dist (environment markers not supported yet)
- Fixed a bug where not enough newlines were inserted between description files


0.1.4 (2011-05-24)
------------------

- Adds support for custom command classes specified in the 'commands' option
  under the [global] section in setup.cfg
- Adds preliminary support for custom compilers specified in the 'compilers'
  option under the [global] section in setup.cfg.  This functionality doesn't
  exist in distutils/setuptools/distribute, so adding support for it is a
  flaming hack.  It hasn't really been tested beyond seeing that the custom
  compilers come up in `setup.py build_ext --help-compiler`, so any real-world
  testing of this feature would be appreciated


0.1.3 (2011-04-20)
------------------

- Adds zest.releaser entry points for updating the version number in a
  setup.cfg file; only useful if you use zest.releaser--otherwise harmless
  (might eventually move this functionality out into a separate product)
- Though version 0.1.2 worked in Python3, use_2to3 wasn't added to the setup.py
  so 2to3 had to be run manually
- Fixed a crash on projects that don't have a description-file option

0.1.2 (2011-04-13)
------------------

- Fixed the self-installation--it did not work if a d2to1 version was not
  already installed, due to the use of `pkg_resources.require()`
- Adds nominal Python3 support
- Fixes the 'classifier' option in setup.cfg

0.1.1 (2011-04-12)
------------------

- Fixed an unhelpful error message when a setup_hook fails to import
- Made d2to1 able to use its own machinery to install itself



