| # | |
| # Copyright 2016 Keunhong Lee | |
| # | |
| # 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 types import FunctionType | |
| from typing import Callable, TypeVar, Union | |
| _WrappedMethod = TypeVar("_WrappedMethod", bound=Union[FunctionType, Callable]) | |
| def final(method: _WrappedMethod) -> _WrappedMethod: | |
| """Decorator to indicate that the decorated method is finalized and cannot be overridden. | |
| The decorator code is executed while loading class. Using this method | |
| should have minimal runtime performance implications. | |
| Currently, only methods with @override are checked. | |
| How to use: | |
| from overrides import final | |
| class SuperClass(object): | |
| @final | |
| def method(self): | |
| return 2 | |
| class SubClass(SuperClass): | |
| @override | |
| def method(self): #causes an error | |
| return 1 | |
| :raises AssertionError: if there exists a match in sub classes for the method name | |
| :return: method | |
| """ | |
| setattr(method, "__final__", True) | |
| return method | |