python把对象输出为字符串，重写 __str__，可方便应用于一些场景

class Test:
    def __init__(self, name):
        self.name = name

    # def __str__(self):
    #     return self.name


t = Test("abc")
print(t)

结果是一个object：<__main__.Test object at 0x0000026C943DA460>

class Test:
    def __init__(self, name):
        self.name = name

    def __str__(self):
        return self.name


t = Test("abc")
print(t)

结果：abc