[Python-Dev] Pre-PEP: Unifying try-except and try-finally

[Russell E. Owen]

In article <972ec5bd05051016285954fec at mail.gmail.com>,
 Timothy Fitz <firemoth at gmail.com> wrote:

> > No, as except clauses can only occur before the finally clause, and 
> > execution
> > should not go backwards.
> 
> This restriction feels a bit arbitrary. I can guarantee someone is
> going to flatten this:
> 
> try:
>     try:
>         A
>     finally:
>         B
> except IOError:
>    C
> 
> A more flexible approach would be to allow finally at the beginning or
> ending of the try statement. A more flexible approach would be to
> allow both, or even finally clauses mixed in.
>
> To me, that's the ugly portion of this proposal, it's quite arbitrary.
> And the alternatives I posted have their own brands of ugly.

I strongly disagree. It makes sense to me, anyway, that "finally" can 
only be the final clause and that it always does exactly what it says: 
execute as the final bit of the try statement.

I think this would be a useful enhancement. It simplifies the published 
documentation a bit (no need to document try/except as a separate entity 
from try/finally) and I have plenty of cases where I'd like to take 
advantage of it.

> Concisely, this is an arbitrary shortcut for an idiom that already
> exists. It seems to me that this shortcut would be redundant if PEP
> 340 or something with similar functionality was accepted.

I do see your point here and I'll be curious to see how this shapes up 
(given the lengthy discussion going on about this tricky proposal).

But I also feel that the unification of try/except and try/finally is 
truly an improvement to the language. To me it feels like a 
simplification -- it removes an artificial, annoying and unnecessary 
split.

-- Russell