Source code for fastr.helpers.lazy_module

# Copyright 2011-2014 Biomedical Imaging Group Rotterdam, Departments of
# Medical Informatics and Radiology, Erasmus MC, Rotterdam, The Netherlands
# 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
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# See the License for the specific language governing permissions and
# limitations under the License.

This module contains the Manager class for Plugins in the fastr system

import sys
from types import ModuleType

[docs]class LazyModule(ModuleType): """ A module that allows content to be loaded lazily from plugins. It generally is (almost) empty and gets (partially) populated when an attribute cannot be found. This allows lazy loading and plugins depending on other plugins. """
[docs] def __init__(self, name, parent, plugin_manager): super(LazyModule, self).__init__(name) self._plugin_manager = plugin_manager self.__dict__.update(vars(parent)) self._parent = parent sys.modules[parent.__name__] = self
[docs] def __repr__(self): return super(LazyModule, self).__repr__().replace('module', 'lazy_module', 1)
[docs] def __getattr__(self, item): """ The getattr is called when getattribute does not return a value and is used as a fallback. In this case we try to find the value normally and will trigger the plugin manager if it cannot be found. :param str item: attribute to retrieve :return: the requested attribute """ try: return super(LazyModule, self).__getattribute__(item) except AttributeError as exception: try: return self._plugin_manager[item] except KeyError: raise exception