Allows using distutils2-like setup.cfg files for a package's metadata with a distribute/setuptools setup.py

## 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 = 0.2.12
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 =
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
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
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.

## 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.

### 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()

• 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

## Project details

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