setup.py 文件源码

def has_environment_marker_support():
    """
    Tests that setuptools has support for PEP-426 environment marker support.

    The first known release to support it is 0.7 (and the earliest on PyPI seems to be 0.7.2
    so we're using that), see: http://pythonhosted.org/setuptools/history.html#id142

    References:

    * https://wheel.readthedocs.org/en/latest/index.html#defining-conditional-dependencies
    * https://www.python.org/dev/peps/pep-0426/#environment-markers
    """
    try:
        return pkg_resources.parse_version(setuptools.__version__) >= pkg_resources.parse_version('0.7.2')
    except Exception as exc:
        sys.stderr.write("Could not test setuptool's version: %s\n" % exc)
        return False