gimme that returned thing.

April 3rd, 2008 by pam | Posted in programming |

Wow, I am kind of an idiot sometimes. In my defense, I have been programming for maybe a year and have zero formal training. I’m pretty lucky to work with the people I work with, though, and I think my one saving grace is that I can usually tell when I’m going down the wrong path and I’m not particularly shy about asking for help before I find myself totally lost in the rabbit hole.

I’m sure everyone else knows this already, but hey, maybe someone is interested in the little shit that trips up Python newbies. So, here’s today’s adventure.

def do_something():
    foo = []
    foo.append("bar")
    return foo

if __name__ == "__main__":
    print foo

Obviously, that doesn’t work. I get a NameError: name ‘foo’ is not defined. But if I declare ‘foo’ outside the function, there’s no problem. Works just fine. I knew that was wrong, though, because no one else has to do that. I tried and tried to figure it out, because obviously I was having scope problems and it seemed like something that would be, well, obvious. But finally I broke down and asked someone, and he said, “wait, you’re not assigning the return value of that function?”

Um. In fact, no. So now I have this:

def do_something():
    foo = []
    foo.append("bar")
    return foo

if __name__ == "__main__":
    baz = do_something()
    print baz

And it works! Pretty lame as adventures go, I know, but it is kind of a major revelation to me.

Tags: n00b, python