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

[François Pinard]

[Guido van Rossum]
> [Nick Coghlan]

> > > What does a try statement with neither an except clause nor a
> > > finally clause mean?

> [Greg Ewing]
>
> > I guess it would mean the same as

> >    if 1:
> >      ...

> I strongly disagree with this.  [...]

Allow me a quick comment on this issue.

It happens once in a while that I want to comment out the except clauses
of a try statement, when I want the traceback of the inner raising, for
debugging purposes.  Syntax forces me to also comment the `try:' line,
and indent out the lines following the `try:' line.  And of course, the
converse operation once debugging is done.  This is slightly heavy.

At a few places, Python is helpful for such editorial things, for
example, allowing a spurious trailing comma at end of lists, dicts,
tuples. `pass' is also useful as a place holder for commented code.

At least, the new proposed syntax would allow for some:

     finally:
         pass

addendum when commenting except clauses, simplifying the editing job for
the `try:' line and those following.


P.S. - Another detail, while on this subject.  On the first message I've read
on this topic, the original poster wrote something like:

    f = None
    try:
        f = action1(...)
    ...
    finally:
        if f is not None:
            action2(f)

The proposed syntax did not repeat this little part about "None", quoted
above, so suggesting an over-good feeling about syntax efficiency.
While nice, the syntax still does not solve this detail, which occurs
frequently in my experience.  Oh, I do not have solutions to offer, but
it might be worth a thought from the mighty thinkers of this list :-)

-- 
François Pinard   http://pinard.progiciels-bpi.ca