Subclass Python list to Validate New Items

Question

I want a python list which represents itself externally as an average of its internal list items, but otherwise behaves as a list. It should raise a TypeError i

Answer 1

Actually the best answer may be: don't.

Checking all objects as they get added to the list will be computationally expensive. What do you gain by doing those checks? It seems to me that you gain very little, and I'd recommend against implementing it.

Python doesn't check types, and so trying to have a little bit of type checking for one object really doesn't make a lot of sense.