From: "João Távora" <joaotavora@gmail.com>
To: Stefan Monnier <monnier@iro.umontreal.ca>
Cc: emacs-devel@gnu.org
Subject: Re: Attaching context info to an error
Date: Tue, 26 Dec 2023 22:43:52 +0000 [thread overview]
Message-ID: <CALDnm53Buy+7oX-nY+no+7Q+EEAfZabr4RwwcJfSGifXXfvb_A@mail.gmail.com> (raw)
In-Reply-To: <jwvh6k4hf18.fsf-monnier+emacs@gnu.org>
On Tue, Dec 26, 2023 at 8:47 PM Stefan Monnier <monnier@iro.umontreal.ca> wrote:
>
> >> I'm playing with `handler-bind` and trying to see how we could make use
> >> of such a functionality in Emacs.
> > *loud cheers*
> [...]
> > Amongst the killer weaponry this gives us is a restart system,
> > finally.
>
> I fail to see the connection, to be honest.
The restarts themselves can be made with simply try/catch,
you're right, but automatically invoking restarts with certain
parameters based on different each error object can only be done
with handler-bind AFAIK.
Also, for restarts to become visible/invisible according to
some information in the condition themselves (the type
of error or some other cookie) we also need handler-bind to
attach that cookie to the condition object.
Typically, a restart gives you the option to try again with
something different (not just try again as I did in this
poc), like if a network connection fails, you're given
the option to try with new credentials, or a different
protocol, etc...
> And why `handler-bind`. IOW, why wait until the error happens before
> pushing the retry onto the list? Why not just:
>
> (defun pm/call-with-retry-restart (outer inner msg fn)
> (catch outer
> (let ((pm/restarts
> (cons (list 'retry msg
> (lambda () (throw inner nil))))))
> (while t
> (catch inner
> (throw outer (funcall fn)))))))
Probably, this was a thinko, or I was trying to simulate visibility
of a restart like I described above, but there are much better
ways to do that.
Anyway, as Gerd suggested, I would suggest at least supporting
EIEIO in this handler-bind. This needn't necessarily clash with
our "error symbols" if the dispatching is done via generic functions
right? The usual performance setbacks of EIEIO object shouldn't
be a problem as conditions are meant to represent exceptional
situations by definition. The counterpart to handler-bind is
handler-case btw (which is more or less our condition-case).
next prev parent reply other threads:[~2023-12-26 22:43 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-12-21 22:30 Attaching context info to an error Stefan Monnier
2023-12-22 6:50 ` Gerd Möllmann
2023-12-22 8:37 ` Gerd Möllmann
2023-12-22 15:58 ` Stefan Monnier
2023-12-28 6:57 ` Gerd Möllmann
2023-12-22 20:56 ` Jens Schmidt
2023-12-22 22:37 ` Stefan Monnier
2023-12-23 3:02 ` João Távora
2023-12-23 3:28 ` João Távora
2023-12-26 20:12 ` Stefan Monnier
2023-12-26 20:47 ` Stefan Monnier
2023-12-26 22:43 ` João Távora [this message]
2023-12-27 6:50 ` Gerd Möllmann
2023-12-27 10:29 ` João Távora
2023-12-27 10:35 ` Gerd Möllmann
2023-12-27 17:50 ` Stefan Monnier
2023-12-27 18:08 ` João Távora
2023-12-27 18:28 ` João Távora
2023-12-27 19:08 ` Stefan Monnier
2023-12-27 19:27 ` João Távora
2023-12-27 20:27 ` Stefan Monnier
2023-12-27 23:08 ` João Távora
2023-12-28 7:05 ` Stefan Monnier
2023-12-28 14:12 ` João Távora
2023-12-28 16:03 ` Stefan Monnier
2023-12-28 17:15 ` João Távora
2023-12-28 19:22 ` Stefan Monnier
2023-12-28 23:53 ` João Távora
2023-12-29 2:54 ` Stefan Monnier
2023-12-29 3:43 ` João Távora
2023-12-29 16:54 ` Stefan Monnier
2023-12-29 17:29 ` João Távora
2023-12-29 17:39 ` João Távora
2023-12-30 4:29 ` Stefan Monnier
2023-12-30 16:45 ` João Távora
2023-12-29 17:19 ` Alan Mackenzie
2023-12-29 17:24 ` João Távora
2023-12-29 17:43 ` Alan Mackenzie
2023-12-29 17:54 ` João Távora
2023-12-29 18:08 ` Alan Mackenzie
2023-12-29 18:45 ` João Távora
2023-12-29 18:35 ` Stefan Monnier
2023-12-29 18:48 ` João Távora
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