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

Previous Next

Full log

Message #20 received at 47677 <at> debbugs.gnu.org (full text, mbox):

From: Mattias Engdegård <mattiase <at> acm.org>
To: Stefan Monnier <monnier <at> iro.umontreal.ca>
Cc: Lars Ingebrigtsen <larsi <at> gnus.org>, 47677 <at> debbugs.gnu.org
Subject: Re: bug#47677: [PATCH] condition-case success continuation
Date: Mon, 12 Apr 2021 21:20:24 +0200

[Message part 1 (text/plain, inline)]

Here is an updated patch that reduces some code duplication in the compiler and fixes an embarrassing bug, and as a bonus, an experimental add-on that allows catching throws in condition-case using the handler syntax

  ((:catch TAG) BODY...)

Unfortunately but unsurprisingly the decision to evaluate the TAG expressions made everything much messier than anticipated. It does work, though, and if you would like to redefine `catch` as the macro

(defmacro catch (tag &rest body)
  (let ((var (gensym)))
    `(condition-case ,var (progn ,@body) ((:catch ,tag) ,var))))

then that will work, too (with minor byte-code inefficiency that could easily be addressed).
Any combination of error, :catch and :success handlers is permitted, making this a very versatile construct.

It may be a good idea to do away with the TAG evaluation since that flexibility isn't likely to be in high demand.

[0001-Add-condition-case-success-handler-bug-47677.patch (application/octet-stream, attachment)]

[catch-in-condition-case.diff (application/octet-stream, attachment)]

[Message part 4 (text/plain, inline)]

Previous Next

GNU bug tracking system
Copyright (C) 1999 Darren O. Benham, 1997,2003 nCipher Corporation Ltd, 1994-97 Ian Jackson.