From: Dmitry Gutov <dgutov@yandex.ru>
To: Stephen Leake <stephen_leake@stephe-leake.org>, emacs-devel@gnu.org
Subject: Re: Allow xref to use other than current major-mode
Date: Tue, 25 Aug 2015 20:05:55 +0300 [thread overview]
Message-ID: <55DCA073.8090308@yandex.ru> (raw)
In-Reply-To: <867fojidv4.fsf@stephe-leake.org>
On 08/25/2015 06:31 PM, Stephen Leake wrote:
> cl-generic.el is preloaded, so we could use a cl-defgeneric, and
> dispatch on (mode (eql <major-mode>)).
A given implementation is, of course, free to use cl-defgeneric and
dispatch on whatever it wants, internally.
> To make such a minor mode work, xref--read-identifier could be a
> cl-defgeneric that dispatches on (project <project-type).
The plan is to consolidate the various -function's as generic method,
dispatching on a single xref-backend value. I haven't got around to this
yet, blocked on find-file-delayed.
> But if it also
> dispatches on (mode (eql <major-mode>)), each backend would have to
> define all combinations; that's a pain.
If a backend needs to dispatch based on the current language, it will.
It will do that inside the method implementations.
But many backends will only need to deal with one language, a couple, or
won't really need to check the language of the current buffer.
> I've started writing such a thing, but it gets defeated by the fact that
> xref--read-identifier uses the buffer-local value of
> xref-identifier-completion-table-function, which is set by elisp-mode
> (or c-mode, etc, or by default to etags). There's no way to change that.
A backend is a combination of xref-find-function, xref-i-c-t-function
and xref-i-a-p-function. If a minor mode changes the current backend, it
would need to set all these variables (but see the planned change
mentioned above).
> We could require the user to manually enable an xref minor mode in each
> buffer, but that's not friendly.
We have "globalized" minor modes, to be used in similar situations.
> I guess a global xref backend could somehow reset that variable, in all
> elisp buffers? Maybe a function on elisp-mode-hook.
A minor mode function is indeed normally added to xxx-mode-hook, whether
it's by user's hand, or somehow automatically.
> So a better approach would be to define a way to disable emacs-lisp-mode
> (and all other major-modes) setting the xref buffer-local variables, so
> that the user choice of xref backend is respected. That would be much
> simpler than having to add a function to all the major mode hooks (most
> of which are unknown at load time).
You're speaking from the standpoint of wanting a single, global xref
backend everywhere for the duration of the Emacs session.
As previous discussions showed, that approach isn't natural for everyone.
> We could define a new global variable xref-global-backend; if nil (the
> default),
We've discussed a very similar proposal, very recently. As long as a
minor mode can take over major mode's setting anyway, there's no point
in adding this kind of explicit override.
> major modes can set xref vars; if non-nil, it indicates which
> particular global backend is in use. It could be a function that returns
> a boolean indicating whether the global backend wants to control xref in
> the current buffer. So a semi-global backend could provide C and Ada
> xref, but not elisp xref, for example. It could be a list of such
> functions; only if all return nil should the major mode set the xref
> vars.
Sounds like an unnecessary complication.
next prev parent reply other threads:[~2015-08-25 17:05 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-08-25 10:00 Allow xref to use other than current major-mode Stephen Leake
2015-08-25 11:48 ` Dmitry Gutov
2015-08-25 12:19 ` João Távora
2015-08-25 12:25 ` David Engster
2015-08-25 14:47 ` Stephen Leake
2015-08-25 15:07 ` David Engster
2015-08-25 15:23 ` Eli Zaretskii
2015-08-25 17:25 ` Dmitry Gutov
2015-08-25 21:17 ` Stephen Leake
2015-08-25 15:31 ` Stephen Leake
2015-08-25 15:41 ` Stephen Leake
2015-08-25 17:05 ` Dmitry Gutov [this message]
2015-08-25 21:13 ` Stephen Leake
2015-08-25 22:11 ` Dmitry Gutov
2015-08-25 22:15 ` Stefan Monnier
2015-08-25 22:29 ` Dmitry Gutov
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