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bug#32956: 26.1.50; t-m-m mark deactivation documentation
From: |
Charles A. Roelli |
Subject: |
bug#32956: 26.1.50; t-m-m mark deactivation documentation |
Date: |
Sun, 07 Oct 2018 16:39:07 +0200 |
> Date: Sun, 7 Oct 2018 01:02:28 +0000 (UTC)
> From: Drew Adams <drew.adams@oracle.com>
>
> > Hmm, deactivate-mark is nil by default -- what effect would setting it
> > to "nil" again have? Is it to counteract the effect of previous
> > function calls within the command, which may have set
> > "deactivate-mark" to "t"?
>
> This is about defining a command that activates the region
> and wants to leave/keep it activated after the command
> is finished.
>
> Consider, as one example, a repeatable command that
> does something with the active region (e.g. indents it).
> Because it is repeatable it wants to keep the region
> activated, for the next action. It needs to do this at
> the end: (setq deactivate-mark nil).
I think changing or adding text in the buffer is what eventually tells
the command loop to deactivate the mark (via the variable
deactivate-mark). The command loop should not do that by default
after each command. For example, from emacs -Q:
M-: (defun foo () (interactive)) RET C-x h M-x foo RET > does NOT deactivate
the mark
M-: (defun foo () (interactive) (insert "text")) RET C-x h M-x foo RET > DOES
deactivate the mark
So, developers should only have to add (setq deactivate-mark nil) to
the end of their command if it is a command that changes or adds
buffer text without wanting to deactivate the mark.
This is explained in the Elisp manual (where it belongs, I think).
But the Emacs manual does lack an index entry for "deactivating the
mark", which seems like an area for improvement.
bug#32956: 26.1.50; t-m-m mark deactivation documentation, Eli Zaretskii, 2018/10/06