From: Eli Zaretskii <eliz@gnu.org>
To: Paul Pogonyshev <pogonyshev@gmail.com>
Cc: emacs-devel@gnu.org
Subject: Re: graceful shutdown of non-interactive Elisp program
Date: Sun, 14 Jun 2020 18:01:10 +0300 [thread overview]
Message-ID: <83imft3d55.fsf@gnu.org> (raw)
In-Reply-To: <CAG7BpaqQ+KZro+v12x3y_v3wcQnB7wnP6qQ66sWDRx7EXEhEkw@mail.gmail.com> (message from Paul Pogonyshev on Sat, 13 Jun 2020 23:42:51 +0200)
> From: Paul Pogonyshev <pogonyshev@gmail.com>
> Date: Sat, 13 Jun 2020 23:42:51 +0200
>
> I'm trying to make a Elisp program that is run in a non-interactive mode, i.e. essentially as `emacs --batch
> --load myfile.el'. A normal way to shutdown terminal programs is with C-c, which is expected to be "graceful"
> shutdown, e.g. the program still has a chance to save files etc.
>
> However, with Elisp I'm not sure how to achieve that except for constantly modifying `kill-emacs-hook', which
> would be a nightmare from coding perspective.
>
> Naively I would expect this print "GOING DOWN" when aborted with C-c:
>
> $ emacs --batch --eval "(unwind-protect (while t) (message \"GOING DOWN\"))"
>
> For example, Python's handler of SIGINT raises an exception within the program, which unwinds the stack
> as usual and, unless caught, cause program termination after cleaning up as expected (e.g. running all
> `finally' clauses and closing all `with' context managers). However, in Elisp, as I understand, there is no way
> to have a say in handling SIGINT other than adding a function to `kill-emacs-hook'.
I don't think I follow. If you want to raise an exception from a
kill-emacs-hook (assuming that you want the unwind-protect forms to do
something), you can do that from kill-emacs-hook, no?
And if you had a say in handling SIGINT, what would you do in the
handler that you cannot do in kill-emacs-hook?
Also, you mention batch mode, but is it relevant? That is, are you
saying that Emacs behaves differently in an interactive session when
it gets a fatal signal?
I'm confused.
next prev parent reply other threads:[~2020-06-14 15:01 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-13 21:42 graceful shutdown of non-interactive Elisp program Paul Pogonyshev
2020-06-13 22:59 ` Joost Kremers
2020-06-14 15:01 ` Eli Zaretskii [this message]
2020-06-14 16:47 ` Paul Pogonyshev
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