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

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From: Mattias Engdegård <mattiase <at> acm.org>
To: Stefan Kangas <stefan <at> marxist.se>
Cc: Lars Ingebrigtsen <larsi <at> gnus.org>, Stefan Monnier <monnier <at> iro.umontreal.ca>, 47677 <at> debbugs.gnu.org
Subject: bug#47677: [PATCH] condition-case success continuation
Date: Thu, 22 Apr 2021 15:58:10 +0200

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

21 apr. 2021 kl. 16.13 skrev Stefan Kangas <stefan <at> marxist.se>:

> Should this be closed, or is there more to do here?

There's the business of fixing `catch` in the same way. (A new bug could be opened for it, but since it's intimately related we might as well do it here.) As mentioned, `catch` has three problems:

- no way to execute code when a throw is caught
- no way to execute code when the body terminates normally
- no way to catch both throws and errors

since neither `catch` nor `condition-case` compose with themselves or each other.
For example, it would be useful to have `pcase` match both the value of an expression as well as throws and errors from it.

Here is a proper patch, essentially a polished version of the previously posted diff. It adds `condition-case` clauses on the form

((:catch TAG-EXPR) BODY...)

where TAG-EXPR is evaluated before the protected form to a tag value, and BODY is executed when that tag is thrown, with the variable bound to the thrown value.

[0001-catch-handlers-in-condition-case-bug-47677.patch (application/octet-stream, attachment)]

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