Re: [Emacs-diffs] /srv/bzr/emacs/trunk r109327: Generalize INTERNAL_FIELD between buffers, keyboards and frames.

[Eli Zaretskii <eliz@gnu.org>]

> Date: Wed, 01 Aug 2012 22:02:27 +0400
> From: Dmitry Antipov <dmantipov@yandex.ru>
> CC: emacs-devel@gnu.org
> 
> > May I suggest to post some kind of design notes, with some details
> > about the above?  I think such preliminary discussions help get all
> > the interested parties up to speed, raise some important issues that
> > are best discovered sooner rather than later, and generally avoid
> > surprises, pleasant or otherwise.
> 
> OK. There are some ideas to share now.

Thanks.

> 3. Premature optimization is the root of all evil. For the beginning,
> I'm trying to implement a hugely overestimated write barrier (e.g. a lot
> of pointer writes are really pointer reads). Of course, it will be notoriously
> slow.

If "notoriously slow" means slow to the degree that it would annoy
people, my suggestion is either do not commit that to the trunk, or
make it switchable (by an #ifdef or by a variable, preferably the
latter).  Otherwise, people will get annoyed and will bombard you with
bug reports, making development harder.

Having the new code switchable at run time is better because it lets
you easily check whether some bug is due to the new code or not.