_compatibility.py 文件源码

def find_module_py33(string, path=None):
    loader = importlib.machinery.PathFinder.find_module(string, path)

    if loader is None and path is None:  # Fallback to find builtins
        try:
            loader = importlib.find_loader(string)
        except ValueError as e:
            # See #491. Importlib might raise a ValueError, to avoid this, we
            # just raise an ImportError to fix the issue.
            raise ImportError("Originally ValueError: " + e.message)

    if loader is None:
        raise ImportError("Couldn't find a loader for {0}".format(string))

    try:
        is_package = loader.is_package(string)
        if is_package:
            module_path = os.path.dirname(loader.path)
            module_file = None
        else:
            module_path = loader.get_filename(string)
            module_file = open(module_path, 'rb')
    except AttributeError:
        # ExtensionLoader has not attribute get_filename, instead it has a
        # path attribute that we can use to retrieve the module path
        try:
            module_path = loader.path
            module_file = open(loader.path, 'rb')
        except AttributeError:
            module_path = string
            module_file = None
        finally:
            is_package = False

    return module_file, module_path, is_package