I'm not a great advocate of recursion - pieces of code that call themselves; most of the examples that I see in books are "training examples" that are overcomplex and achieve results that could much more easily be achieved by alternative means. I'm not telling you NEVER to use recursion - sometimes (such as when you're travesing XML, for example) it does work very well.

Anyway - one of the dangers of code that calls itself is that it will get into an endless loop and so there will be a limit to the number of levels deep you can go. That defaults to 1000 in Python, but you can increase it - there's a setrecursionlimit method in the sys class. Here's an example of it in use:

# Python defaults to a recursion limit of 1000 levels, which
# you can change - see this example. Beware - it's said
# that the standard windows build has a hard limit of 2000
# that you cannot exceed!

import sys

sys.setrecursionlimit(1500)

def zz(x):
  if x < 1: return 0
  result = zz(x-1) + x
  return result

print zz(1200)

Without that extra line, you get the error message
RuntimeError: maximum recursion depth exceeded
when you run the code
(written 2006-11-02 01:10:25)

 Y105 - Python - Functions, Modules and Packages

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