Re: A strange issue with buffer-undo-list

[Marcin Borkowski <mbork@mbork.pl>]

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