metaclasses

Question 1

define class with metaclass

Answer 1

class Widget(object, metaclass=type):
	pass

Question 2

class definition in detail

Answer 2

namespace = metaclass.\_\_prepare\_\_(name, bases, **kwargs)
Wiget = metaclass.\_\_new\_\_(metaclass, name, bases, namespace, **kwargs)
metaclass.\_\_init\_\_(Widget, name, bases, namespace, **kwargs)

Question 3

when __prepare__ override ?

Answer 3

cusomize the type or initial value of the namespace mapping

Question 4

when __new__ override?

Answer 4

allocate and optionally configure new class object

Question 5

where **kwargs comes from?

Answer 5

from class definition
class MyClass(metaclass=MyMetaclass, kwarg1 ="asdf):

Question 6

metamethod difference from @classmethod

Answer 6

metamethod is not visible from instance

Question 7

a = MyClass() What method invoked?

Answer 7

MyClass.__class__.__call__()