setup.py 文件源码

def has_environment_marker_support():
    #type: () -> bool
    """
    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.io/en/latest/index.html#defining-conditional-dependencies
    * https://www.python.org/dev/peps/pep-0426/#environment-markers
    Method extended from pytest. Credit goes to developers there.
    """
    try:
        from pkg_resources import parse_version
        return parse_version(setuptools.__version__) >= parse_version('0.7.2')
    except Exception as exc:
        sys.stderr.write("Could not test setuptool's version: %s\n" % exc)
        return False