3.3 python关于元类及property装饰器的使用

1、元类的使用

import inspect


class B(type):

    def __new__(mcs, name, bases, attrs):
        """
        @:param msc 元类自身
        @:param name 类名，不是元类的name
        @:param bases 继承父类的元组集合，不是元类的父类
        @:param attrs 类的属性字典集合
        """

        for attr_name, attr_value in attrs.items():

            if attr_name == 'say' and callable(attr_value):
                # 通过inspect可以获取，类方法中的参数
                print(inspect.signature(attr_value).parameters)
        return super().__new__(mcs, name, bases, attrs)


class C:
    pass


class A(C, metaclass=B):

    def say(self, name):
        print(name)

2、@property

class D:

    def __init__(self, name):
        self._name = name

    @property
    def g(self):
        return self._name

    # 必须以被property标记的方法开始
    @g.setter
    def g(self, v):
        self._name = v


d = D('hell')
print(d.g)
d.g = 222
print(d.g)