From: Stefan Monnier <monnier@iro.umontreal.ca>
To: Nic Ferrier <nferrier@ferrier.me.uk>
Cc: emacs-devel@gnu.org
Subject: Re: non-local exits with signal and condition-case
Date: Sun, 02 Jun 2013 20:02:16 -0400 [thread overview]
Message-ID: <jwvhahgf4uo.fsf-monnier+emacs@gnu.org> (raw)
In-Reply-To: <87ehckjiyr.fsf@ferrier.me.uk> (Nic Ferrier's message of "Sun, 02 Jun 2013 22:33:48 +0100")
> This is a heavily simplified version of something I just wrote for the
> new elnode based emacswiki:
Oh, I misunderstood, then: you're simulating "exceptions", which are
called "signals" in Elisp, so you definitely want to use `signal' and
`condition-case' here, rather than catch/throw.
The only inconvenient is that signal names are global, so you need to
use a name of the form "<prefix>-redirect". I guess you could use an
uninterned signal name, but it might be tricky to make use of that in
a convenient way.
>> You probably want to cons `errv' in front of inherits-list.
> I thought about that before I sent it - I think you are probably
> right. But my understanding is that you don't need the symbol to be
> present; you can disassociate the symbol used to send the signal from
> the symbol(s) used to capture it.
Yes, if you don't put `errv' in there, indeed you dissociate the two, so
you can't catch an "errv" with "errv" but only with one of its parents.
> I think (as you suggest) a define-signal form should probably not
> support that directly because it seems quite counter intuitive.
Exactly. While it's technically possible, no signal does that and
I can't think of any situation where someone would want to make use of
such a "feature". So it's more likely to be a source of bugs and
bug-reports than anything else.
>> We could add it to subr.el (tho I'd call it define-signal).
> Shall I send patches then?
Yes. Please send them to bug-gnu-emacs@gnu.org.
Stefan
next prev parent reply other threads:[~2013-06-03 0:02 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-06-02 16:24 non-local exits with signal and condition-case Nic Ferrier
2013-06-02 18:52 ` Stefan Monnier
2013-06-02 21:33 ` Nic Ferrier
2013-06-03 0:02 ` Stefan Monnier [this message]
2013-06-03 15:54 ` Davis Herring
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
List information: https://www.gnu.org/software/emacs/
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=jwvhahgf4uo.fsf-monnier+emacs@gnu.org \
--to=monnier@iro.umontreal.ca \
--cc=emacs-devel@gnu.org \
--cc=nferrier@ferrier.me.uk \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
Code repositories for project(s) associated with this public inbox
https://git.savannah.gnu.org/cgit/emacs.git
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).