List as FIFO in for loop

[duncan smith]

malkarouri wrote:
> Hi everyone,
> 
> I have an algorithm in which I need to use a loop over a queue on
> which I push values within the loop, sort of:
> 
> while not(q.empty()):
>     x = q.get()
>     #process x to get zero or more y's
>     #for each y:
>     q.put(y)
> 
> The easiest thing I can do is use a list as a queue and a normal for
> loop:
> 
> q = [a, b, c]
> 
> for x in q:
>     #process x to get zero or more y's
>     q.append(y)
> 
> It makes me feel kind of uncomfortable, though it seems to work. The
> question is: is it guaranteed to work, or does Python expect that you
> wouldn't change the list in the loop?
> 

I have used exactly the same approach.  I think it's a clean (even 
elegant) solution.  I'd be surprised if it ceased to work in some future 
implementation of Python, but I don't know if that's absolutely guaranteed.

Duncan