| # 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 | |
| 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, warning=None): # pylint: disable=super-on-old-class | |
| self._local_name = local_name | |
| self._parent_module_globals = parent_module_globals | |
| self._warning = warning | |
| super(LazyLoader, self).__init__(name) | |
| def _load(self): | |
| """Load the module and insert it into the parent's globals.""" | |
| # 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) |