From the cookbook, this time. It satisfies the requirements nicely ;)
http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/496691 def tail_recursion(g): ''' Version of tail_recursion decorator using no stack-frame inspection. ''' loc_vars ={"in_loop":False,"cnt":0} def result(*args, **kwd): loc_vars["cnt"]+=1 if not loc_vars["in_loop"]: loc_vars["in_loop"] = True while 1: tc = g(*args,**kwd) try: qual, args, kwd = tc if qual == 'continue': continue except (TypeError, ValueError): loc_vars["in_loop"] = False return tc else: if loc_vars["cnt"]%2==0: return ('continue',args, kwd) else: return g(*args,**kwd) return result @tail_recursion def factorial(n, acc=1): "calculate a factorial" if n == 0: return acc res = factorial(n-1, n*acc) return res -- http://mail.python.org/mailman/listinfo/python-list
