Python -- 面向对象(7) -- metaclass及相关魔术方法

obj = Foo()时，内部魔术方法执行过程：

 

class MyType(type):
    def __init__(self,what,bases=None,dict=None):
        super(MyType, self).__init__(what,bases,dict)
        print('1.MyType_init')

    # def __call__(self,*args,**kwargs):
    #     print('2.MyType_call')
    #     r = self.__new__(self, *args, **kwargs)
    #     print('4.',r)
    #     s = self.__init__(self)

class Foo(object,metaclass=MyType):
    def __init__(self):
        print('5.Foo_init')

    def __new__(cls,*args, **kwargs):
        print('3.Foo_new')
        return object.__new__(cls,*args,**kwargs)

    def normal_method(self):
        print('6.普通方法')

#Foo()
abc = Foo()
print(abc)

输出：

1.MyType_init
3.Foo_new
5.Foo_init
<__main__.Foo object at 0x0000029D2679D908>

 

class MyType(type):
    def __init__(self,*args, **kwargs):
        print('1.MyType_init')

    def __call__(self,*args,**kwargs):
        print('2.MyType_call')
        r = self.__new__(self, *args, **kwargs)
        print('4.',r)
        s = self.__init__(self)

class Foo(object,metaclass=MyType):
    def __init__(self):
        print('5.Foo_init')

    def __new__(cls,*args, **kwargs):
        print('3.Foo_new')
        return object.__new__(cls,*args,**kwargs)

    def normal_method(self):
        print('6.普通方法')

obj = Foo()

输出：

1.MyType_init
2.MyType_call
3.Foo_new
4. <__main__.Foo object at 0x000002571FE6D8D0>
5.Foo_init