标签：包装 多重继承 val UI elf 多重 self set key
为达成目的，经常会在类中将一些内置方法进行重写，最常见的例如__setattr__，下面就通过内置属性，来查看重写会带来什么变化
先定义一个测试用的类，代码如下
class base: def __init__(self): pass inspect.getmembers(base): # 查看内置属性
打印结果如下
(‘__class__‘, <class ‘type‘>) (‘__delattr__‘, <slot wrapper ‘__delattr__‘ of ‘object‘ objects>) (‘__dict__‘, mappingproxy({‘__module__‘: ‘__main__‘, ‘__init__‘: <function base.__init__ at 0x0069A0C0>, ‘__getattr__‘: <function base.__getattr__ at 0x0069A108>, ‘__dict__‘: <attribute ‘__dict__‘ of ‘base‘ objects>, ‘__weakref__‘: <attribute ‘__weakref__‘ of ‘base‘ objects>, ‘__doc__‘: None})) (‘__dir__‘, <method ‘__dir__‘ of ‘object‘ objects>) (‘__doc__‘, None) (‘__eq__‘, <slot wrapper ‘__eq__‘ of ‘object‘ objects>) (‘__format__‘, <method ‘__format__‘ of ‘object‘ objects>) (‘__ge__‘, <slot wrapper ‘__ge__‘ of ‘object‘ objects>) (‘__getattr__‘, <function base.__getattr__ at 0x0069A108>) (‘__getattribute__‘, <slot wrapper ‘__getattribute__‘ of ‘object‘ objects>) (‘__gt__‘, <slot wrapper ‘__gt__‘ of ‘object‘ objects>) (‘__hash__‘, <slot wrapper ‘__hash__‘ of ‘object‘ objects>) (‘__init__‘, <function base.__init__ at 0x0069A0C0>) (‘__init_subclass__‘, <built-in method __init_subclass__ of type object at 0x00699030>) (‘__le__‘, <slot wrapper ‘__le__‘ of ‘object‘ objects>) (‘__lt__‘, <slot wrapper ‘__lt__‘ of ‘object‘ objects>) (‘__module__‘, ‘__main__‘) (‘__ne__‘, <slot wrapper ‘__ne__‘ of ‘object‘ objects>) (‘__new__‘, <built-in method __new__ of type object at 0x1E1FADB8>) (‘__reduce__‘, <method ‘__reduce__‘ of ‘object‘ objects>) (‘__reduce_ex__‘, <method ‘__reduce_ex__‘ of ‘object‘ objects>) (‘__repr__‘, <slot wrapper ‘__repr__‘ of ‘object‘ objects>) (‘__setattr__‘, <slot wrapper ‘__setattr__‘ of ‘object‘ objects>) (‘__sizeof__‘, <method ‘__sizeof__‘ of ‘object‘ objects>) (‘__str__‘, <slot wrapper ‘__str__‘ of ‘object‘ objects>) (‘__subclasshook__‘, <built-in method __subclasshook__ of type object at 0x00699030>) (‘__weakref__‘, <attribute ‘__weakref__‘ of ‘base‘ objects>)
找到__setattr__，发现他是一个 slot wrapper（是否可以理解为插口包装）
‘__setattr__‘, <slot wrapper ‘__setattr__‘ of ‘object‘ objects>
对__setattr__进行重写，在赋值的时候打印key与value
def __setattr__(self , key , value): print(key,value) self.__dict__[key] = value
再次打印，发现__setattr__变为了普通的方法
(‘__setattr__‘, <function base.__setattr__ at 0x0227F108>)
总结：在重写内置方法时，内置方法会从slot wrapper变为普通的function，slot wrapper-->function
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疑问：如果有类继承，父类重写，子类是否也继承？
1 class base: # 父类 2 def __init__(self): 3 pass 4 5 def __setattr__(self, key, value): 6 print(key, value) 7 self.__dict__[key] = value 8 9 class Foo(base): # 子类 10 def __init__(self): 11 pass
情况1： 子类Foo未重写__setattr__，父类base与子类Foo的内置属性中，__setattr__完全相同
# 父类base (‘__setattr__‘, <function base.__setattr__ at 0x0243E108>) # 子类Foo (‘__setattr__‘, <function base.__setattr__ at 0x0243E108>)
情况2，子类Foo重写__setattr__方法，二者不同
# 父类base (‘__setattr__‘, <function base.__setattr__ at 0x0243E108>) # 子类Foo (‘__setattr__‘, <function Foo.__setattr__ at 0x022BE198>)
,总结：在有继承关系时， 1：父类重写内置方法会影响到所有的子类
2：子类将方法重写后与继承特性相同，会覆盖父类的相同的方法
3：在多重继承中，如果父类都重写了该方法，则会继承写在前面的那个父类的方法（具体请参考我的另一片关于多重继承的文章）
标签：包装 多重继承 val UI elf 多重 self set key
原文地址：http://www.cnblogs.com/bloath/p/7305856.html
