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Re: Lisp primitives and their calling of the change hooks
From: |
Alan Mackenzie |
Subject: |
Re: Lisp primitives and their calling of the change hooks |
Date: |
Wed, 10 Jan 2018 18:45:22 +0000 |
User-agent: |
Mutt/1.7.2 (2016-11-26) |
Hello, Stefan.
On Tue, Jan 09, 2018 at 15:07:58 -0500, Stefan Monnier wrote:
> > The way I see it, to announce in advance that the original region will be
> > deleted (by calling b-c-f for it) is suboptimal.
> But not incorrect.
> > If the decompression fails, we need to balance that b-c-f with
> > a "fake" a-c-f call.
> No, we don't. It's still within the rules to announce an upcoming
> change with b-c-f and then not to carry through (i.e. not make any
> changes and not call a-c-f).
It's debatable whether it's within the rules or not. The rules, which
we so carefully crafted a few days ago, say, in part; "The arguments to
`before-change-functions' will enclose a region in which the individual
changes are made, ...". There will never be any changes made in the
quasi-deleted region, so to leave it without a balanceing a-c-f call
could be construed as against the rules.
I'm not saying it's a sensible debate to have, though. More to the
point is that the b-c-f call may have made changes to the buffer which
need to be undone. (Somebody, sometime, is going to try calling this
primitive in a C++ Mode buffer just to see what happens. What they
should see is no buffer change, particularly not in the text
properties.)
Although, with unbalanced b/a-c-f being permitted anyway, for a mode
whose b-c-f does make buffer changes, there'll have to be, say, an entry
in post-command-hook anyway, to catch these unbalanced calls.
> Stefan
--
Alan Mackenzie (Nuremberg, Germany).
- Re: Lisp primitives and their calling of the change hooks, (continued)
- Re: Lisp primitives and their calling of the change hooks, Eli Zaretskii, 2018/01/08
- Re: Lisp primitives and their calling of the change hooks, Stefan Monnier, 2018/01/08
- Re: Lisp primitives and their calling of the change hooks, Eli Zaretskii, 2018/01/08
- Re: Lisp primitives and their calling of the change hooks, Stefan Monnier, 2018/01/09
- Re: Lisp primitives and their calling of the change hooks, Eli Zaretskii, 2018/01/09
- Re: Lisp primitives and their calling of the change hooks, Alan Mackenzie, 2018/01/09
- Re: Lisp primitives and their calling of the change hooks, Eli Zaretskii, 2018/01/09
- Re: Lisp primitives and their calling of the change hooks, Alan Mackenzie, 2018/01/10
- Re: Lisp primitives and their calling of the change hooks, Alan Mackenzie, 2018/01/12
- Re: Lisp primitives and their calling of the change hooks, Stefan Monnier, 2018/01/09
- Re: Lisp primitives and their calling of the change hooks,
Alan Mackenzie <=
- Re: Lisp primitives and their calling of the change hooks, Stefan Monnier, 2018/01/10
- Re: Lisp primitives and their calling of the change hooks, Alan Mackenzie, 2018/01/10
- Re: Lisp primitives and their calling of the change hooks, Stefan Monnier, 2018/01/10
- Re: Lisp primitives and their calling of the change hooks, Alan Mackenzie, 2018/01/10
- Re: Lisp primitives and their calling of the change hooks, Stefan Monnier, 2018/01/11
- Re: Lisp primitives and their calling of the change hooks, Alan Mackenzie, 2018/01/11
- Re: Lisp primitives and their calling of the change hooks, Stefan Monnier, 2018/01/11
- Re: Lisp primitives and their calling of the change hooks, Alan Mackenzie, 2018/01/11
- Re: Lisp primitives and their calling of the change hooks, Stefan Monnier, 2018/01/11
- Re: Lisp primitives and their calling of the change hooks, Alan Mackenzie, 2018/01/11