Re: A strange issue with buffer-undo-list

[Marcin Borkowski]

On 2021-02-26, at 01:53, Michael Heerdegen <michael_heerdegen@web.de> wrote:

> Marcin Borkowski <mbork@mbork.pl> writes:
>
>> Still, these "change groups" seem a strange feature to me - they are
>> hardly ever used in Emacs itself, right?
>
> Seems so.  Where they are used - e.g. in the implementation of
> `transpose-subr', they are important however.  You wouldn't want that
> undoing a transposition would happen in multiple steps uncovering
> implementation details.

Agreed, although I don't think undo would kick in within one command
(without explicit undo boundaries).

> Could be in other places they would also be appropriate but were
> forgotten.  May also be that automatic undo amalgamation conceals cases
> were change group applications are missing.

As above - isn't it rather that unless you put explicit undo boundaries,
they are only inserted when the command loop takes over?

>
> BTW, in master your code example now works without errors, the problem
> has been fixed (by Stefan).  And your code also works as you intend.  I
> have tried.  It doesn't work as intended however when using
> `undo-tree-mode' (another minor bug I would say).

Thanks for the answer, and sorry for the delay.  Yes, I noticed it's
fixed; I don't use undo-tree.

Best,

-- 
Marcin Borkowski
http://mbork.pl