a good explanation

[Diez B. Roggisch]

> Something that is being missed is the idea of changing conditions. A
> for loop assumes known boundaries.
> 
> def condition_test():
>   # check socket status
>   # return true if socket good, false otherwise
> 
> while condition_test():
>    # do stuff
> 
> allows the loopiing code to react to changing conditions. Which of
> couse is why we like to keep while loops around ;-0

You can always use break to, well, break out of the loop - and as for is 
working over iterables which might very well be generators that deliver 
an infinite amount of data, the break-condition can (and often will, 
even if one used while) work on the current object instead of some 
otherwise unsused index.

So above becomes:


for item in items:
     if condition(item):
         break
     ...

where the while would be still pretty ugly IMHO :)


Diez