__init__.py 文件源码

def get_installed_version(dist_name, lookup_dirs=None):
    """Get the installed version of dist_name avoiding pkg_resources cache"""
    # Create a requirement that we'll look for inside of setuptools.
    req = pkg_resources.Requirement.parse(dist_name)

    # We want to avoid having this cached, so we need to construct a new
    # working set each time.
    if lookup_dirs is None:
        working_set = pkg_resources.WorkingSet()
    else:
        working_set = pkg_resources.WorkingSet(lookup_dirs)

    # Get the installed distribution from our working set
    dist = working_set.find(req)

    # Check to see if we got an installed distribution or not, if we did
    # we want to return it's version.
    return dist.version if dist else None