1. Understanding
Metaclasses

2. • Computer science student at TU Berlin
• Software Developer at Charité - Universitätsmedizin
Berlin
• Involved in Flask, Werkzeug, Babel and many other
open source projects

3. What is an object?

4. What is an instance?

5. What is a class?

6. What is a metaclass?

7. How does an instance
attribute of a classes
metaclass affect that class?

8. How is this different
from a class attribute?

9. How does a method of a
classes metaclass affect
that class?

10. How is this different from
a class method defined
with @classmethod?

11. Is there anything
unique to metaclasses?

12. def __new__(cls, name, bases, namespace, **kwargs)!
!
def __init__(self, name, bases, namespace, **kwargs)

13. How is this different
from class decorators?

14. @classmethod
def __prepare__(cls, name, bases, **kwargs)

15. def __call__(self, *args, **kwargs)

16. (Sane) use cases?
• Form libraries
• ORMs
• Anything declarative

17. Q&A