Is there an overhead when nesting functions in Python?

Question

In Python, if I have a child function within a parent function, is the child function \"initialised\" (created) every time the parent function is called? Is there any overhe

Answer 1

The other answers are great and really answer the question well. I wanted to add that most inner functions can be avoided in python using for loops, generating functions, etc.

Consider the following Example:

def foo():
    # I need to execute a function on two sets of arguments:
    argSet1 = (1, 3, 5, 7)
    argSet2 = (2, 4, 6, 8)

    # A Function could be executed on each set of args
    def bar(arg1, arg2, arg3, arg4):
        return (arg1 + arg2 + arg3 + arg4)

    total = 0
    for argSet in [argSet1, argSet2]:
      total += bar(*argSet)
    print( total )

    # Or a loop could be used on the argument sets
    total = 0
    for arg1, arg2, arg3, arg4 in [argSet1, argSet2]:
        total += arg1 + arg2 + arg3 + arg4
    print( total )

This example is a little goofy, but I hope you can see my point nonetheless. Inner functions are often not needed.