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# Copyright 2015 The TensorFlow Authors. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# ==============================================================================
"""A LazyLoader class."""
from __future__ import absolute_import
from __future__ import division
from __future__ import print_function
import importlib
import types
class LazyLoader(types.ModuleType):
"""Lazily import a module, mainly to avoid pulling in large dependencies.
`contrib`, and `ffmpeg` are examples of modules that are large and not always
needed, and this allows them to only be loaded when they are used.
"""
# The lint error here is incorrect.
def __init__(self, local_name, parent_module_globals, name): # pylint: disable=super-on-old-class
self._local_name = local_name
self._parent_module_globals = parent_module_globals
super(LazyLoader, self).__init__(name)
def _load(self):
# Import the target module and insert it into the parent's namespace
module = importlib.import_module(self.__name__)
self._parent_module_globals[self._local_name] = module
# Update this object's dict so that if someone keeps a reference to the
# LazyLoader, lookups are efficient (__getattr__ is only called on lookups
# that fail).
self.__dict__.update(module.__dict__)
return module
def __getattr__(self, item):
module = self._load()
return getattr(module, item)
def __dir__(self):
module = self._load()
return dir(module)
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