《零基础入门学习python》045笔记：魔法方法—属性访问

汪蛋

知识点一：优雅地访问属性：gtrattr

class C():
    def __init__(self):
        self.x = 'X-man'

>>> c = C()
>>> c.x
'X-man'
>>> getattr(c, 'y', '没有这个属性')
'没有这个属性'

知识点二：优雅地访问属性：property

class C():
    def __init__(self, size=10):
        self.size = size
    def getSize(self):
        return self.size
    def setSize(self, value):
        self.size = value
    def delSize(self):
        del self.size
    x = property(getSize, setSize, delSize)

>>> c = C()
>>> c.x
10
>>> c.x = 1
>>> c.x
1
>>> c.size
1
>>> del c.x
>>> c.size
Traceback (most recent call last):
  File "<pyshell#14>", line 1, in <module>
    c.size
AttributeError: 'C' object has no attribute 'size'

知识点三：魔法方法的属性访问

class C():
    def __getattribute__(self, name):
        print("getattribute")
        return super().__getattribute__(name)

知识点四：小程序练习

class Rectangle:
    def __init__(self, width=0, height=0):
        self.width = width
        self.height = height

    def __setattr__(self, name, value):
        if name == 'square':
            self.width = value
            self.height = value
        else:
            super().__setattr__(name, value)
            #或者super这一条语句换成下面
            #self.__dict__[name] = value
            #如果写成self.name = value就会进入死循环
            
    def getArea(self):
        return self.width * self.height

>>> r1 = Rectangle()
>>> r1.getArea()
0
>>> r1 = Rectangle(2, 3)
>>> r1.getArea()
6
>>> r1.square = 10
>>> r1.width
10
>>> r1.height
10
>>> r1.getArea()
100
>>> r1.__dict__
{'width': 10, 'height': 10}

wddn1

感谢楼主