bug#8447: Undoing M-x revert-buffer

[Kevin Rodgers <kevin.d.rodgers@gmail.com>]

On 4/8/11 9:54 AM, Hrvoje Nikšić wrote:
> It would be nice to be able to undo a revert-buffer operation.
>
> I've just had a situation where I used M-x revert-buffer, and
> immediately wanted to see the old version again.  (I wanted to briefly
> compare the old and new contents, which only differed in several
> characters.)  I routinely pressed C-_, and got a "no undo data" message
> in the echo area.  For the shortest instant I was surprised, but I
> quickly remembered that M-x revert-buffer clears the undo stack, and
> that it has always worked that way.
>
> But I would like to question this design choice.  What I wanted to do
> was not really unreasonable.  The buffer held several kilobytes of data,
> and my computer has gigabytes of memory at its disposal, enough room to
> hold the buffer contents literally a million times over.  If you think
> about it, reverting an existing buffer is just another operation on
> buffer text, not that different than M-x erase-buffer followed by M-x
> insert-file, which would happily remember everything.
>
> If the maintainers agree in principle, I'd like to look into patching
> revert-buffer so it records the revert as it would any other change to
> the buffer text.

In the short term, or if the maintainers do not agree to Hrvoje's proposal,
how about adding a warning to the "Revert buffer from file FILE? " yes-or-no-p
prompt?

-- 
Kevin Rodgers
Denver, Colorado, USA