#!/usr/bin/python -tt
# -*- coding: utf-8 -*-
'''
Copyright 2014-2015 Teppo Perä
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.
'''
from pytraits.trait_composer import add_traits
[docs]def extendable(target):
"""
Decorator that adds function for object to be extended using traits.
NOTE: The 'add_traits' function this extendable decorator adds contains
behavior that differs from usual function behavior. This method
alters its behavior depending is the function called on a class
or on an instance. If the function is invoked on class, then the
class gets updated by the traits, affecting all new instances
created from the class. On the other hand, if the function is invoked
on an instance, only that instance gets the update, NOT whole class.
See complete example from:
pytraits/examples/extendable_function_class_vs_instance.py
>>> @extendable
... class ExampleClass:
... pass
...
>>> hasattr(ExampleClass, 'add_traits')
True
>>> class InstanceExample:
... pass
...
>>> instance_example = InstanceExample()
>>> _ = extendable(instance_example)
>>> hasattr(instance_example, 'add_traits')
True
"""
class TypeFunction:
def __init__(self):
self._target_object = None
def __call__(self, *args, **kwargs):
add_traits(self._target_object, *args, **kwargs)
def __get__(self, instance, clazz):
self._target_object = instance or clazz
return self
target.add_traits = TypeFunction()
return target
if __name__ == '__main__':
import doctest
doctest.testmod()