Re: Combining face and map stuff

[Eli Zaretskii <eliz@gnu.org>]

> From: Stefan Monnier <monnier@iro.umontreal.ca>
> Cc: Eli Zaretskii <eliz@gnu.org>,  emacs-devel@gnu.org
> Date: Wed, 06 Oct 2010 01:43:03 +0200
> 
> >>> It sounds like he's saying it would use their union, with a
> >>> property-specific function used to compute that union.
> >>> [and that the union computation could be done at "property setting time"
> >>> rather than at display time, to avoid speed problems.]
> >> I'm probably missing something here: if the union is computed at
> >> put-text-property time, then how is this different from what we have
> >> now?  That union will have all the properties of the character lumped
> >> together, just like what we have now, right?  What am I missing?
> 
> You're missing that in order o properly update the merge when some
> property is added/removed in a plane, all users of text properties will
> have to follow some new conventions.

When I said "what am I missing", I meant the advantages of what you
propose.  Having to follow some new conventions sounds like the price
one has to pay for having these advantages, but what are the
advantages themselves?

If the new protocol itself is the advantage, then perhaps what I'm
missing is the essence of the problems that you proposal is trying to
solve.