From: Eli Zaretskii <eliz@gnu.org>
To: Phil Sainty <psainty@orcon.net.nz>
Cc: emacs-devel@gnu.org
Subject: Re: Enable derived modes to run their own very-early 'change-major-mode-hook' code
Date: Sun, 21 Apr 2019 09:23:18 +0300 [thread overview]
Message-ID: <83ftqbanc9.fsf@gnu.org> (raw)
In-Reply-To: <85237c18-768d-089b-221a-fe70b0ba4379@orcon.net.nz> (message from Phil Sainty on Sun, 21 Apr 2019 14:35:35 +1200)
[I'm moving this to emacs-devel, as the bug tracker doesn't sound
appropriate for such discussions. Please send any followups here.]
> From: Phil Sainty <psainty@orcon.net.nz>
> Date: Sun, 21 Apr 2019 14:35:35 +1200
>
> The library I'm working on (so-long.el) defines a major mode
> which needs to remember various buffer-local values as they were
> in the original mode, *before* my major mode takes effect.
>
> I'm currently using `change-major-mode-hook' for this, but it has
> occurred to me that it would be nicer if this hook code of mine
> only ever ran in the case where it is useful (i.e. the major mode
> being changed to is in fact my mode). `change-major-mode-hook'
> has no knowledge of the mode which has just been invoked, so it
> must necessarily run for *every* mode change -- which isn't
> relevant to my library in the vast majority of cases.
>
> I think `change-major-mode-hook' would more commonly be used by
> modes to handle any subsequent 'unloading' needs of that same
> mode in case it gets replaced later on (i.e. the mode body could
> set a buffer-local hook value), so my scenario of the new mode
> wanting to know things about the previous mode is doubtless a bit
> of a niche case; but I thought I'd raise it for discussion.
Did you consider using major-mode-suspend and major-mode-restore?
next prev parent reply other threads:[~2019-04-21 6:23 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-21 2:35 bug#35351: 27.0.50; Enable derived modes to run their own very-early 'change-major-mode-hook' code Phil Sainty
2019-04-21 2:45 ` Phil Sainty
2019-04-21 6:01 ` Richard Stallman
2019-04-21 6:23 ` Eli Zaretskii [this message]
2019-04-21 20:54 ` Stefan Monnier
2019-04-22 8:16 ` Phil Sainty
2019-04-22 14:39 ` Stefan Monnier
2019-04-22 23:18 ` Phil Sainty
2019-04-22 23:31 ` Phil Sainty
2019-04-23 2:08 ` Stefan Monnier
2019-04-23 3:52 ` Phil Sainty
2019-04-23 11:59 ` Stefan Monnier
2019-04-22 14:41 ` Stefan Monnier
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