# Copyright 2021 Arthur Coqué, Pôle OFB-INRAE ECLA, UR RECOVER
#
# 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.
Slightly adapted from the one of TensorFlow,
see: https://github.com/tensorflow/tensorflow/blob/master/tensorflow/python/util/lazy_loader.py
"""
import importlib
import types
[docs]class LazyLoader(types.ModuleType):
"""Lazily import a module, mainly to avoid pulling in large dependencies."""
def __init__(self, local_name, parent_module_globals, name):
self._local_name = local_name
self._parent_module_globals = parent_module_globals
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)