__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:
            six.raise_from(ValueError('{}.__loader__ is not set'.format(name)), None)

        spec = _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


# This should be in all python >2.7