Setuptools platform specific dependencies

Question

Is there any way to tell setuptools or distribute to require a package on a specific platform?

In my specific case, I'm using readline, which comes as part of the standard library on Unix systems, but on Windows I need the pyreadline module to replace that functionality (cf. this question). If I just put it in the requirements It also installs on Unix systems where it's completely useless.

Answer 1

setup.py is simply a python script. You can create dynamic dependencies in that script:

import platform

setup_requires = ['foo', 'bar']

if platform.system() == 'Windows':
    setup_requires.append('pyreadline')

setup(
    # ...
    setup_requires=setup_requires,
)

Answer 2

While the answer given by Martijn Pieters was totally valid at the time, Python packaging has changed a lot since then.

The preferred format to distribute packages is using wheels*. Using wheels it is not possible to run Python code during installation.

Wheel use metadata version two as specified in PEP 0427. Environment markers can be used to specify platform specific dependencies.

Setuptools allows to specify these environment markers as extras_require keys. The following example script depends on pyreadline for Windows systems and on pyxdg for Linux distributions.

#!/usr/bin/env python
from setuptools import setup

setup(
    name='spam',
    version='0.0.1',
    extras_require={
        ':sys_platform == "win32"': [
            'pyreadline'
        ],
        ':"linux" in sys_platform': [
            'pyxdg'
        ]
    })

*Also release an sdist, so platforms which can't use wheel can still install your package.

Answer 3

Other answers are valid and probably more convenient if supporting old setuptools versions is required, but there have been some advancements:

Recent versions of setuptools accept PEP 508 style dependency specification:

setup(
    # ...
    install_requires=[
        'pyreadline; platform_system == "Windows"',
    ],
)

Choose the right parameter:

• install_requires: what other distributions are needed for the current distribution to work correctly
• extras_require: a dictionary mapping the names of optional features to a list of their requirements
• setup_requires: other distributions that need to be present for the setup script to run correctly Note: projects listed in setup_requires will NOT be automatically installed. They are simply downloaded to the ./.eggs directory if they’re not locally available already.

There is also an alternative way for supplying these parameters through setup.cfg file. See the documentation for more info.

PEP 518 introduces a new and more capable way of specifying setup_requires in pyproject.toml file:

[build-system]
# Minimum requirements for the build system to execute.
requires = ['setuptools>"38.3.0"', 'wheel']  # PEP 508 specifications.

The feature was implemented in pip 10.0.0b1. Using it one will be able to automatically install and update build system requirements.

Answer 4

from setuptools import setup


setup(
    install_requires=(['pymsgbox', 'PyTweening>=1.0.1', 'Pillow', 'pyscreeze']
                    + ["python3-xlib; sys_platform == linux"]
                    + ["python-xlib; sys_platform == linux2"]
                    + ["pyobjc-core; sys_platform == darwin"]
                    + ["pyobjc; sys_platform == darwing"]
                    ),
)

This will install speicific versions of libraries depending on whether its linux2 (for a linux system using python2), linux (for a linux system using python3), darwin (for a MacOS system)