Re: The *Warnings* buffer and undo

[David Kastrup]

Richard Stallman <address@hidden> writes:

>     I don't think it is a good idea to let-bind buffer-undo-list here:
>     instead it should generally be set to t in the buffer.
>
>     Otherwise undo information will be recorded sparsely (for example, for
>     user input), leading to inconsistent results.
>
> That was my first reaction, but then it occurred to me that recording
> undo info only for user editing might be just the right thing.

But the undo info will then not be able to _undo_ older changes, but
will rather damage the buffer in unpredictable ways if you try using
it.

Unrecorded changes turn the existing undo history useless.  While it
could conceivably be nice if user changes could be undone, this won't
work out.  The best that a program could do in this regard is set
buffer-undo-list to t before doing its changes, and to nil afterwards.

That way the user will be able to undo his changes as long as no new
output appears.

-- 
David Kastrup, Kriemhildstr. 15, 44793 Bochum