策略模式优化if-else

class Calculator:def __init__(self):self.strategy = Nonedef set_strategy(self, strategy):self.strategy = strategydef calculate_result(self, num1, num2):return self.strategy.execute(num1, num2)class Add:def execute(self, num1, num2):return num1 + num2class Sub:def execute(self, num1, num2):return num1 - num2class Mul:def execute(self, num1, num2):return num1 * num2class Div:def execute(self, num1, num2):return num1 / num2# 使用示例
calculator = Calculator()
calculator.set_strategy(Add())
print(calculator.calculate_result(6, 3))  # 输出：9