#!/usr/bin/env PYTHONHASHSEED=1234 python3 # Copyright 2014-2019 Brett Slatkin, Pearson Education Inc. # # 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. # Example 8 # Check types in this file with: python -m mypy class Counter: def __init__(self) -> None: self.value: int = 0 # Field / variable annotation def add(self, offset: int) -> None: value += offset # Oops: forgot "self." def get(self) -> int: self.value # Oops: forgot "return" counter = Counter() counter.add(5) counter.add(3) assert counter.get() == 8