GNU bug report logs - #47677
[PATCH] condition-case success continuation

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Message #29 received at 47677 <at> debbugs.gnu.org (full text, mbox):

From: Lars Ingebrigtsen <larsi <at> gnus.org>
To: Mattias Engdegård <mattiase <at> acm.org>
Cc: Stefan Monnier <monnier <at> iro.umontreal.ca>, 47677 <at> debbugs.gnu.org
Subject: Re: bug#47677: [PATCH] condition-case success continuation
Date: Wed, 14 Apr 2021 11:29:21 +0200

Mattias Engdegård <mattiase <at> acm.org> writes:

> Oh, it was just proof-of-concept code to show that such a
> generalisation would be possible should it be desired later. It's not
> part of the immediate proposal. Sorry about the confusion.

Oh, OK.  :-)

> Our present `catch` has the same flaw as `condition-case` in that it
> does not give access to the success continuation, leading to hacks
> similar to the one you mentioned.

Yes, that's true.

> We could extend `catch` instead, maybe like this:
>
>   (catch TAG :in BODY-FORM :success VAR SUCCESS-FORM)
>
> but what if you want to catch multiple tags, or both throws and
> errors? The constructs don't compose; nesting them hides the success
> continuation of the inner forms.

Yeah, I think extending `catch' here would be less than optimal, but I
don't really have any suggestions here -- I use `throw/catch' so little
that I have no gut feeling about what I see as being useful.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

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