ez_setup.py 文件源码

def use_setuptools(version=DEFAULT_VERSION, download_base=DEFAULT_URL,
                   to_dir=os.curdir, download_delay=15):
    # making sure we use the absolute path
    to_dir = os.path.abspath(to_dir)
    was_imported = 'pkg_resources' in sys.modules or \
        'setuptools' in sys.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.VersionConflict:
        e = sys.exc_info()[1]
        if was_imported:
            sys.stderr.write(
            "The required version of setuptools (>=%s) is not available,\n"
            "and can't be installed while this script is running. Please\n"
            "install a more recent version first, using\n"
            "'easy_install -U setuptools'."
            "\n\n(Currently using %r)\n" % (version, e.args[0]))
            sys.exit(2)
        else:
            del pkg_resources, sys.modules['pkg_resources']    # reload ok
            return _do_download(version, download_base, to_dir,
                                download_delay)
    except pkg_resources.DistributionNotFound:
        return _do_download(version, download_base, to_dir,
                            download_delay)