ez_setup.py 文件源码

def use_setuptools(version=DEFAULT_VERSION, download_base=DEFAULT_URL,
        to_dir=os.curdir, download_delay=15):
    to_dir = os.path.abspath(to_dir)
    rep_modules = 'pkg_resources', 'setuptools'
    imported = set(sys.modules).intersection(rep_modules)
    try:
        import pkg_resources
    except ImportError:
        return _do_download(version, download_base, to_dir, download_delay)
    try:
        pkg_resources.require("setuptools>=" + version)
        return
    except pkg_resources.DistributionNotFound:
        return _do_download(version, download_base, to_dir, download_delay)
    except pkg_resources.VersionConflict as VC_err:
        if imported:
            msg = textwrap.dedent("""
                The required version of setuptools (>={version}) is not available,
                and can't be installed while this script is running. Please
                install a more recent version first, using
                'easy_install -U setuptools'.

                (Currently using {VC_err.args[0]!r})
                """).format(VC_err=VC_err, version=version)
            sys.stderr.write(msg)
            sys.exit(2)

        # otherwise, reload ok
        del pkg_resources, sys.modules['pkg_resources']
        return _do_download(version, download_base, to_dir, download_delay)