Re: [T. V. Raman] read-only modes should be using buffer-disable-undo?

[Luc Teirlinck]

T. V. Raman wrote:

   I wasn't refering to the optimization with respect to grouping small
   chunks of output; rather, I was indicating that perhaps we could avoid
   having undo information altogether in read-only modes like man-mode.

On the one hand, there probably are many read-only modes that only
enable undo because it is enabled by default and the author just
forgot to disable it.  Clearly, we should fix those if we find them.
On the other hand, undo is not necessarily useless in read-only
buffers, because they can be made writable with C-x C-q.  Dired even
provides functionality to use the undo info without having to do C-x C-q.

For instance is undo info in the Buffer Menu useless?  That is not
obvious.  It certainly is not as useful as in writable buffers.  But
suppose for instance that you delete a buffer in the Buffer Menu with
`d' and `x'.  You then realize that you probably inadvertently deleted
the wrong buffer.  You can do C-x C-q and then undo.  This will not
bring the buffer back automatically, but you can see which buffer you
deleted.  You can then do `g' to update the Buffer Menu again.  The
entire procedure even works if you auto revert the Buffer Menu (in the
CVS version), because deleting a buffer with d and x marks the buffer
modified, protecting it from further reverts until the user reverts it
by hand.

Sincerely,

Luc.