What is the benefit to define a function in a function in python?

Question

I encountered this piece of python code (pasted below) on effbot and I was wondering:

Why defining a function within a function?

import          


        

Answer 1

Often the main reason of such code is function closures. It is powerful thing that is applicable not only to Python. E.g. JavaScript gains a lot from them.

Some points about closures in Python - closures-in-python.

Answer 2

Why defining a function within a function?

To keep it isolated. It's only used in this one place. Why define it more globally when it's used locally?

Answer 3

It's just another way of breaking down a large function into smaller pieces without polluting the global namespace with another function name. Quite often the inner function isn't a stand-alone so doesn't rightfully belong in the global namespace.