Re: Undo-boundary in emacs

[Phillip Lord]

Narendra Joshi <narendraj9@gmail.com> writes:
> I have been trying to figure out where in the source of emacs this is
> happening:
> https://emacs.stackexchange.com/questions/17578/why-does-modification-in-another-buffer-create-undo-boundary-in-current-buffer
>
> I am trying to understand what were the design goals that caused such
> things to happen?
>
> Why does change in a buffer cause every other buffer to have a
> undo-boundary? What would happen if this wasn't the case?


This doesn't happen in Emacs-25, largely to address the use case you are
describing.

It was caused by this code in undo.c

if (current_buffer != last_undo_buffer)
    Fundo_boundary ();
last_undo_buffer = current_buffer;

Most of the code handling automatic undo boundaries is now in simple.el.

Phil