pkg_resources.py 文件源码

def _handle_ns(packageName, path_item):
    """Ensure that named package includes a subpath of path_item (if needed)"""
    importer = get_importer(path_item)
    if importer is None:
        return None
    loader = importer.find_module(packageName)
    if loader is None:
        return None
    module = sys.modules.get(packageName)
    if module is None:
        module = sys.modules[packageName] = imp.new_module(packageName)
        module.__path__ = []
        _set_parent_ns(packageName)
    elif not hasattr(module,'__path__'):
        raise TypeError("Not a package:", packageName)
    handler = _find_adapter(_namespace_handlers, importer)
    subpath = handler(importer,path_item,packageName,module)
    if subpath is not None:
        path = module.__path__
        path.append(subpath)
        loader.load_module(packageName)
        module.__path__ = path
    return subpath