How do I mark a Python package as Python 2 only?

Question

I have a Python package that only runs on Python 2. It has the following classifiers in its setup.py:

setup(
    # ...
    classifiers=[
        'Programming Language :: Python',
        'Programming Language :: Python :: 2',
        'Programming Language :: Python :: 2 :: Only',
    ])

However, if I create a virtualenv with Python 3, pip happily installs this package.

How do I prevent the package being installed? Should my setup.py throw an error based on sys.version_info? Can I stop pip even downloading the package?

Asked By: Wilfred Hughes

||

Source

Answer 1

In setup.py, add this:

import sys
if sys.version_info[0] != 2:
    sys.stderr.write("This package only supports Python 2.n")
    sys.exit(1)

Answered By: Lennart Regebro

Answer 2

In newer versions of setuptools and pip, if you’re using setup.py, here’s how to specify a requirement of Python 2 only (specifically Python 2.7):

from setuptools import setup

setup(
    name="my_package_name",
    python_requires='>=2.7,<3.0',
    # ...
)

It would also be good to include classifiers, like this:

setup(
    name="my_package_name",
    python_requires='>=2.7,<3.0',
    classifiers=[
        "Programming Language :: Python :: 2.7",
        "Programming Language :: Python :: 2 :: Only",
    ],
)

Answered By: Flimm

How do I mark a Python package as Python 2 only?

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