d2to1 0.2.6

Introduction

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 = 0.1.1
author = Erik M. Bray
author-email = embray at stsci.edu
summary = Allows using distutils2-like setup.cfg files for a package's metadata
 with a distribute/setuptools setup.py
description-file = README
license = BSD
requires-dist = setuptools
classifier =
    Development Status :: 4 - Beta
    Environment :: Plugins
    Framework :: Setuptools Plugin
    Intended Audience :: Developers
    License :: OSI Approved :: BSD License
    Operating System :: OS Independent
    Programming Language :: Python
    Topic :: Software Development :: Build Tools
    Topic :: Software Development :: Libraries :: Python Modules
    Topic :: System :: Archiving :: Packaging

[files]
packages = d2to1

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.

Changes