Local Variables in Functions
"How do I use local variables in a function within a class? (I do not want to use self.x, as this makes the instance have variables. I want variables local to my function, that get destroyed at the end of it.) I can only think of using del at the end of the function, is there a better way?"
Local variables only ever define names within their scope, and these names do not appear in the surrounding class or module. Consider this function:
def f(x, y, z): a = x + y + z print "Done!" return a
The names x, y and z come to life as the function f is called, pointing to the objects supplied as arguments to f. When f is finished executing, the names x, y and z are forgotten, but the objects they pointed to might still be around, of course. Here, we use a variable a in the function; this also gets forgotten at the end of the function, but the object a pointed to is returned to the caller.
In short, you always get local variables in Python unless you use the global keyword. You can always use del to make Python forget names, but this is done automatically at the end of function execution for all names in the local scope of that function.