Python type class metaclass

'type' 是 python built-in metaclass

其餘繼承自 ‘type’的class均可以是 Metaclass

子類能夠繼承父類的metaclass

然而 __metaclass__屬性不能繼承

__metaclass__能夠定義成任何返回instance of 'type' callable

 

 

__new__(cls, ...)  : create instance of cls

__init__(self, ...) ：instance already created and set properties to this instance