Behavior of evaporate

[Masatake YAMATO]

> > > I was thinking of suggesting that but wasn't sure whether it'd work.
> > > Does it ?  If it does, it's probably the simplest alternative, indeed.
> > 
> > `evaporate' doesn't work I expect. So I introduced suboverlays property to
> > manage overlay deletion.
> 
> I'm not sure exactly what you're saying, but the overlay `evaporate'
> feature definitely works (unless it's recently been broken)...

(progn (setq xxx 1)
       (setq o (make-overlay 0 0))
       (overlay-put o 'modification-hooks (lambda (ov dummy b e l)
                                            (setq xxx 0)))
       (overlay-put o 'evaporate t)
       xxx)
=> 1

Result I expected is 0.
So I can know an overlay is dead.
Do I misunderstand?

Masatake YAMATO