v2ex

gistfile1.txt

class MyType(type): 
    def __init__(cls, what, bases=None, dict=None): 
        print 'call myType.__init__()'
        print "class name:"+what  
        print "class bases:"+str(bases) 
        print "class attributions:"+str(dict)
        super(MyType,cls).__init__(what, bases, dict)
    def __new__(cls, name, bases, attrs): 
        print "call MyType.__new__()"
        return type.__new__(cls, name, bases, attrs) 
class Foo(object): 
    __metaclass__ = MyType #1 
    def __init__(self, name=None): 
        self.name = name 
        print "Foo.__init__ self=", self
        print "Foo self.name=", self.name 
    def __new__(cls, *args, **kwargs): 
        print "Foo.__new__ cls=", cls
        return(object.__new__(cls, *args, **kwargs)) 
    def __call__(self, cls): 
        print "Foo.__call__ cls=", cls
        print "Foo.__call__ self=", self
    def func(self): 
        print 'function is there' 

if __name__ == '__main__': 
    print "---------test1---------"  #3 
    obj2=Foo() #4 

输出
all MyType.__new__()
call myType.__init__()
class name:Foo
class bases:(<type 'object'>,)
class attributions:{'__module__': '__main__', '__metaclass__': <class '__main__.MyType'>, '__new__': <function __new__ at 0x1081ed3
98>, 'func': <function func at 0x1081ed488>, '__call__': <function __call__ at 0x1081ed410>, '__init__': <function __init__ at 0x10
81ed320>}
---------test1---------
Foo.__new__ cls= <class '__main__.Foo'>
Foo.__init__ self= <__main__.Foo object at 0x108187250>
Foo self.name= None