Overlay evaporates when it should not

Overlay evaporates when it should not

[Peter Whaite]

The Elisp manual says of the overlay evaporate property:

`evaporate'
     If this property is non-`nil', the overlay is deleted automatically
     if it becomes empty (i.e., if its length becomes zero).  However,
     if the overlay is _already_ empty, `evaporate' does not delete it.

I find that it _does_ get deleted if the overlay is already empty...

(let (ov1)
  (save-current-buffer
    (set-buffer (get-buffer-create "*bugsme*"))
    (erase-buffer)
    (remove-overlays)

    (insert "123456789")
    (setq ov1 (make-overlay 2 2)) ; Has zero length
    (print (list 'before-evaporate (overlays-in (point-min) (point-max) )))
    (overlay-put ov1 'evaporate t)
    (print (list 'after-evaporate (overlays-in (point-min) (point-max))))
    ))

Results...

(before-evaporate (#<overlay from 2 to 2 in *bugsme*>))

(after-evaporate nil)



-- 
Peter Whaite (http://whaite.ca)

Re: Overlay evaporates when it should not

[Richard Stallman]

    The Elisp manual says of the overlay evaporate property:

    `evaporate'
	 If this property is non-`nil', the overlay is deleted automatically
	 if it becomes empty (i.e., if its length becomes zero).  However,
	 if the overlay is _already_ empty, `evaporate' does not delete it.

Foverlay_put has explicit code to delete an empty overlay
if you give it a non-nil evaporate property.  It has been there
for 10 years.  So I'll change the manual.

Thanks.