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Re: A strange issue with buffer-undo-list
From: |
Marcin Borkowski |
Subject: |
Re: A strange issue with buffer-undo-list |
Date: |
Mon, 08 Mar 2021 22:43:15 +0100 |
User-agent: |
mu4e 1.1.0; emacs 28.0.50 |
On 2021-02-25, at 06:28, Emanuel Berg via Users list for the GNU Emacs text
editor <help-gnu-emacs@gnu.org> wrote:
> Marcin Borkowski wrote:
>
>>>> Is there a way to get the "state" of the change group to
>>>> only cancel it if it was not finished?
>>>
>>> I think yes, it's called `atomic-change-group' - see how
>>> that macro is implemented.
>>
>> Ah, that's simple and clever. Thank you.
>>
>> Still, these "change groups" seem a strange feature to me -
>> they are hardly ever used in Emacs itself, right?
>
> Maybe people just don't understand the docstring:
>
> Like ‘progn’ but perform BODY as an atomic change group.
> This means that if BODY exits abnormally, all of its changes
> to the current buffer are undone. This works regardless of
> whether undo is enabled in the buffer.
>
> This mechanism is transparent to ordinary use of undo;
> if undo is enabled in the buffer and BODY succeeds, the
> user can undo the change normally.
Well, I understand that. But isn't it strange that almost no code in
Emacs itself uses this?
Best,
--
Marcin Borkowski
http://mbork.pl