On Sun, Sep 27, 2009 at 8:53 PM, pylearner <for_pyt...@yahoo.com> wrote: <snip> > ------------------------------------------------------------------- > > Traceback (most recent call last): > File "<pyshell#2>", line 1, in <module> > toss_winner() > File "C:/Python26/toss_winner.py", line 7, in toss_winner > coin_toss = coin_toss() > UnboundLocalError: local variable 'coin_toss' referenced before > assignment > > --------------------------------------------------------------- > > # toss_winner.py > > from coin_toss import coin_toss > > def toss_winner(): > > coin_toss = coin_toss()
When Python sees this assignment to coin_toss as it compiles the toss_winner() function, it marks coin_toss as a local variable and will not consult global scope when looking it up at runtime (this is an implementation optimization that leaks into the language level). Hence, when the function is executed, Python does a fast lookup of coin_toss in the local scope, finds it has not been assigned to, and raises the error you're seeing, not falling back to and examining the global variable scope. To fix the problem, rename the variable so its name differs from that of the coin_toss() function. That way, Python won't optimize the lookup and will consult the global scope when it goes to resolve coin_toss() in toss_winner(). Cheers, Chris -- http://blog.rebertia.com -- http://mail.python.org/mailman/listinfo/python-list
