8.2 __getattr__、__getattribute__魔法函数

__getattr__

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

    def __getattr__(self, item):
        return 'Not found attribute %s' % item

if __name__ == '__main__':
    user = User('linda')
    print(user.age) # Not found attribute age

• __getattr__, 在查找不到属性的时候调用
• 类似 else 机制

class User:
    def __init__(self, info=None):
        if not info:
            info = {}
        self.info = info

    def __getattr__(self, item):
        return self.info[item]


if __name__ == '__main__':
    user = User({'name': 'linda', 'age': 18})
    print(user.name)
    print(user.age)

• 神奇的代理操作

__getattribute__

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

    def __getattribute__(self, item):
        return 'get_attribute'


if __name__ == '__main__':
    user = User('linda')
    print(user.name)    # get_attribute
    print(user.test)    # get_attribute
    print(user.other)   # get_attribute

• 只要调用属性，就会触发 __getattribute__
• 把持了整个属性调用入口，尽量不要重写这个方法
• 写框架时会涉及到