Re: Retrieve front-advance from make-overlay

["Lennart Borgman (gmail)" <lennart.borgman@gmail.com>]

David Kastrup wrote:
> "Lennart Borgman (gmail)" <lennart.borgman@gmail.com> writes:
> 
>> Stefan Monnier wrote:
>>>> Is it possible to retrieve from an overlay the parameters front-advance and
>>>> rear-advance that was given to make-overlay?
>>>> Without that it is not possible to make a new copy of an overlay AFAICS.
>>> The source code of `copy-overlay' answers this question.
>> Thanks. Indeed it does ;-)  -- BTW copy-overlay is not mentioned in Info.
> 
> (defun overlay-polarities (ov)
>   (let ((buf (overlay-buffer ov))
>         (start (overlay-start ov))
>         (end (overlay-end ov)))
>      (unwind-protect
>         (with-temp-buffer
>            (move-overlay ov 1 1)
>            (insert " ")
>            (list (> (overlay-start ov) 1)
>                  (> (overlay-end ov) 1)))
>        (move-overlay ov buf start end))))
> 
> This at least has the advantage of not touching the original buffer.
> But it is tasteless nevertheless.


Thanks David, I did not that one. I will try it.