On 8/07/20 12:45 AM, Chris Angelico wrote:
On Tue, Jul 7, 2020 at 10:28 PM Frank Millman <fr...@chagford.com> wrote:
Hi all
After iterating over a sequence, the final element is still accessible.
In this case, the variable 'i' still references the integer 4.
Yes, it's guaranteed. It isn't often useful; but the variant where
there's a "break" in the loop most certainly is. If you hit the break,
the iteration variable will still have whatever it had at the end.
This is a great use of 'else' (arguably the primary use of it). You do
something like:
for thing in iterable:
if want(thing): break
else:
thing = None
If the iterable is empty, you go to the else. If you don't find the
thing you want, you go to the else. But if you find it and break,
thing has the thing you wanted.
It wasn't clear if the OP was interested in the value of the pertinent
index or that of the indexed element from the iterable/sequence.
However, the techniques apply - adding enumerate() if the source is a
collection (for example).
Am impressed to see a constructive use of the else: clause! It is a most
pythonic construction used in that mode.
OTOH/IMHO, one of the harder philosophical lessons to learn, is that (in
Python at least) an exception is not necessarily an error - as in
'catastrophe'! Accordingly, there are many examples where 'success' in
such a search-pattern might be terminated with raise.
The 'calling routine'/outer-block would then be able to utilise a
try...except...else...finally structure - arguably both 'richer' and
better-understood by 'the average pythonista' than for...else/while...else
(per previous discussions 'here')
Your thoughts?
Apologies to OP, if am 'hi-jacking' original post.
--
Regards =dn
--
https://mail.python.org/mailman/listinfo/python-list
