Subject: Re: bug#30823: 25.3; modification-hooks of overlays are not run in some cases

From: Eli Zaretskii <[email-masked]>
Date: Sun, 19 Aug 2018 17:46:55 +0300

> From: Stefan Monnier <[email-masked]>
> Cc: Noam Postavsky <[email-masked]>, [email-masked],
>         [email-masked]
> Date: Sat, 18 Aug 2018 23:48:02 -0400
> 
> > Can we turn the table and ask whether it makes sense to delete an
> > overlay from the modification hooks of that same overlay?
> 
> Yes, it very much does make sense: e.g. you want to keep track of
> a "region unmodified" status, so you place an overlay over that region
> with a modification hook that sets a variable to nil to indicate that
> the region was modified, and once that is done there's no point in
> keeping the overlay any more so you can delete it immediately from that
> modification-hook.

I see that I tried too hard to be gentle, and that must have made my
question unclear, because that's not what I was asking.  I was asking
whether we want to support code which does this, because maybe it is
unreasonable to delete an overlay from within its modification hook.