Python面向对象之异常捕获（一）--

# 添加偶数到列表中:这个类继承了内置的list对象
class EvenOnly(list):
    def append(self, integer):
        # If the integer is not a int type, raise a TypeError
        if not isinstance(integer, int):
            raise TypeError("Only integers can be added")
        # If the integer is not a even number, raise a ValueError
        if integer % 2:
            raise ValueError("Only even numbers can be added")
        super().append(integer)

# 测试
e = EvenOnly()
e.append("a string")
e.append(3)
e.append(2)