__init__.py 文件源码

def find_loader(name, path=None):
    """Return the loader for the specified module.

    This is a backward-compatible wrapper around find_spec().

    This function is deprecated in favor of importlib.util.find_spec().

    """
    warnings.warn('Use importlib.util.find_spec() instead.',
                  DeprecationWarning, stacklevel=2)
    try:
        loader = sys.modules[name].__loader__
        if loader is None:
            raise ValueError('{}.__loader__ is None'.format(name))
        else:
            return loader
    except KeyError:
        pass
    except AttributeError:
        raise ValueError('{}.__loader__ is not set'.format(name)) from None

    spec = _bootstrap._find_spec(name, path)
    # We won't worry about malformed specs (missing attributes).
    if spec is None:
        return None
    if spec.loader is None:
        if spec.submodule_search_locations is None:
            raise ImportError('spec for {} missing loader'.format(name),
                              name=name)
        raise ImportError('namespace packages do not have loaders',
                          name=name)
    return spec.loader