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Of the use of setup.cfg instead of setup.py


26/12/2017     permalink     linked site


I upload python packages on pypi on a regular basis since a few years. Since today, i never found anything helpful in the official packaging documentations.

Because there is plenty of it, and as soon as you start a real project, you somehow end up in a corner case that the doc covers, if ever, superficially.

And, today, i found consecutively (and unexpectedly) two things.

  1. This funny presentation (slides) from pycon.fr 2017, where many interesting tools are presented, after a very efficient explanation of setup.{cfg,py}
  2. The linked doc page, that is litterally the first packaging-related official documentation i found helpful.

So, i started the migration of graffunc and its direct application rofetta, with the constraint to use zest.releaser, the final tool presented in the presentation, that do about everything.

One big change to me was the usage of setup.cfg instead of setup.py. (Not so) Surprisingly, it's much more efficient and easy ; and the py is now two lines long (see below for an example). Just one caveat: you have to cheat a little if you want to install the requirements without passing by the complete setuptools machinery. Just put that line in your Makefiles or in your bash aliases, and you can forget about it.

I however one weird problem quickly, since i followed the presentation blindly, and therefore forgot to add few lines they didn't talk about. The problem was, after installation in another repository of graffunc, that any import of graffunc itself would fail with an ImportError: No module named 'graffunc'.

So, here is my working setup.py:

from setuptools import setup

setup()

Which is quite simple and easy to maintain (i will probably reuse the very same for most of my projects, now). And here is my working setup.cfg for the graffunc package:

[metadata]
name = graffunc
version = 0.2.2
description = high level graph of function
long_description = file: README.mkd
url = https://github.com/aluriak/graffunc
license = GPL
keywords = graph, function, data structure
classifiers =
        Development Status :: 2 - Pre-Alpha
        Intended Audience :: Science/Research
        License :: OSI Approved :: GNU General Public License (GPL)
        Natural Language :: English
        Programming Language :: Python :: 3
        Programming Language :: Python :: 3.4
        Topic :: Software Development :: Libraries :: Python Modules

[options]
zip_safe = False
include_package_data = True
packages = find:
install_requires =
    pytest>=3.1.2
    networkx==1.11

You will note the [option] part, populated with one absolute line: packages = find:, which allow python to look for your package and include it correctly. Without that, you will encounter the ImportError.

I would expect zest.releaser to detect and warn me about a so absurd error. But it didn't, and i'm so happy that i found the right doc page so quickly, i had to share :)