PTY wrote:
> Which is better?
>
> lst = [1,2,3,4,5]
>
> while lst:
> lst.pop()
>
> OR
>
> while len(lst) > 0:
> lst.pop()
Here's another reason not to use "if lst". Say you have a function
that looks like this:
def process_values(lst):
if not lst:
return
do_expensive_initialization_step()
for item in lst:
do_something_with(item)
do_expensive_finalization_step()
That works, right? No problem, right?
What if you called the function like this:
process_values(x.strip() for x in values_lst)
Oops, now we've just gone through an expensive initialization and
finalization for nothing (since values_lst was empty). Maybe some
subtle bugs introduced. If we're lucky, the finalization step will
throw an exception.
If we had used "if len(list)>0", we'd have gotten a nice exception
telling us that a generator is not welcome. Then we'd have changed the
argument to a list comprehension, or better, changed the function to
work for any iterator.
Carl Banks
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