元类

一切的类都是通过type这个类来创建的，例如：

 1 class Foo:
 2     a = 1
 3     pass
 4 
 5 
 6 print(type(Foo))
 7 print(Foo.__dict__)
 8 
 9 
10 def __init__(self, name, age):
11     self.name = name
12     self.age = age
13 
14 
15 f1 = type('crazy', (object,), {'a': 1, '__init__': __init__})
16 print(type(f1))
17 print(f1.__dict__)
18 ff = f1('alex',18)
19 print(ff.name)
20 print(ff.age)
21 输出：
22 <class 'type'>
23 {'__module__': '__main__', 'a': 1, '__dict__': <attribute '__dict__' of 'Foo' objects>, '__weakref__': <attribute '__weakref__' of 'Foo' objects>, '__doc__': None}
24 <class 'type'>
25 {'a': 1, '__init__': <function __init__ at 0x00978A00>, '__module__': '__main__', '__dict__': <attribute '__dict__' of 'crazy' objects>, '__weakref__': <attribute '__weakref__' of 'crazy' objects>, '__doc__': None}
26 alex
27 18
 1 class Mytype(type):
 2     def __init__(self, a, b, c):
 3         print(a)
 4         print(b)
 5         print(c)
 6 
 7     def __call__(self, *args, **kwargs):
 8         obj = object.__new__(self)
 9         self.__init__(obj, *args, **kwargs)
10         return obj
11 
12 
13 class Foo(metaclass=Mytype):  # Foo = Mytype(Foo,'Foo',(),{})
14     def __init__(self, name, age):
15         self.name = name
16         self.age = age
17 
18 
19 f1 = Foo('alex', 28)
20 print(f1.__dict__)
21 输出：
22 Foo
23 ()
24 {'__module__': '__main__', '__qualname__': 'Foo', '__init__': <function Foo.__init__ at 0x00698A00>}
25 {'name': 'alex', 'age': 28}

 

posted @ 2020-03-16 21:05  竹石2020  阅读(92)  评论(0)    收藏  举报