prefix notation parsing in python

Question

Right off the bat - no, this is NOT homework.

I would like to write a prefix notation parser in python (for sums presently)... for example

if given: + 2 2 it would return: 4

ideas?

Answer 1

def prefix(input):
  op, num1, num2 = input.split(" ")
  num1 = int(num1)
  num2 = int(num2)
  if op == "+":
    return num1 + num2
  elif op == "*":
    return num1 * num2
  else:
    # handle invalid op
    return 0

print prefix("+ 2 2")

prints 4, also included a multiplication operator just to show how to expand it.