GNU bug report logs - #59996
30.0.50; Overlays section of Elisp manual still states that overlays scale linearly

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Ihor Radchenko <yantar92 <at> posteo.net>
To: bug-gnu-emacs <at> gnu.org
Subject: 30.0.50; Overlays section of Elisp manual still states that
 overlays scale linearly
Date: Mon, 12 Dec 2022 09:53:51 +0000

Hi,

I am still seeing the following clause in the 41.9 Overlays section of
Elisp manual:

       The visual effect of an overlay is the same as of the corresponding
    text property (*note Text Properties::).  However, due to a different
    implementation, overlays generally don’t scale well (many operations
    take a time that is proportional to the number of overlays in the
    buffer).  If you need to affect the visual appearance of many portions
    in the buffer, we recommend using text properties.

Should it be removed now, when overlays are equally performance with
text properties?

In GNU Emacs 30.0.50 (build 1, x86_64-pc-linux-gnu, GTK+ Version
 3.24.35, cairo version 1.17.6) of 2022-12-07 built on localhost
Repository revision: f0e118d3f676afe39df29663399d4bbe8f53f208
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 11.0.12101004
System Description: Gentoo Linux


-- 
Ihor Radchenko // yantar92,
Org mode contributor,
Learn more about Org mode at <https://orgmode.org/>.
Support Org development at <https://liberapay.com/org-mode>,
or support my work at <https://liberapay.com/yantar92>

Message #10 received at 59996-done <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: Ihor Radchenko <yantar92 <at> posteo.net>
Cc: 59996-done <at> debbugs.gnu.org
Subject: Re: bug#59996: 30.0.50;
 Overlays section of Elisp manual still states that overlays scale
 linearly
Date: Mon, 12 Dec 2022 15:39:31 +0200

> From: Ihor Radchenko <yantar92 <at> posteo.net>
> Date: Mon, 12 Dec 2022 09:53:51 +0000
> 
> I am still seeing the following clause in the 41.9 Overlays section of
> Elisp manual:
> 
>        The visual effect of an overlay is the same as of the corresponding
>     text property (*note Text Properties::).  However, due to a different
>     implementation, overlays generally don’t scale well (many operations
>     take a time that is proportional to the number of overlays in the
>     buffer).  If you need to affect the visual appearance of many portions
>     in the buffer, we recommend using text properties.
> 
> Should it be removed now, when overlays are equally performance with
> text properties?

Yes.  I removed it.

I guess that entire section should be audited for inaccuracies now;
reviews and patches are welcome.

Thanks.

Message #13 received at 59996-done <at> debbugs.gnu.org (full text, mbox):

From: Ihor Radchenko <yantar92 <at> posteo.net>
To: Eli Zaretskii <eliz <at> gnu.org>
Cc: 59996-done <at> debbugs.gnu.org
Subject: Re: bug#59996: 30.0.50; Overlays section of Elisp manual still
 states that overlays scale linearly
Date: Tue, 13 Dec 2022 10:42:17 +0000

Eli Zaretskii <eliz <at> gnu.org> writes:

> I guess that entire section should be audited for inaccuracies now;
> reviews and patches are welcome.

Another part that requires update:


       Emacs stores the overlays of each buffer in two lists, divided around
    an arbitrary center position.  One list extends backwards through the
    buffer from that center position, and the other extends forwards from
    that center position.  The center position can be anywhere in the
    buffer.
    
     -- Function: overlay-recenter pos
         This function recenters the overlays of the current buffer around
         position POS.  That makes overlay lookup faster for positions near
         POS, but slower for positions far away from POS.
    
       A loop that scans the buffer forwards, creating overlays, can run
    faster if you do ‘(overlay-recenter (point-max))’ first.

    
‘after-string’/‘before-string’ property description might mention that
string are not displayed if the end/beginning of the overlay is not
displayed for some reason.

Also, it might be worth highlighting that unlike text properties,
overlays advance regardless whether insert or insert-and-inherit is used
to insert the buffer text.

-- 
Ihor Radchenko // yantar92,
Org mode contributor,
Learn more about Org mode at <https://orgmode.org/>.
Support Org development at <https://liberapay.com/org-mode>,
or support my work at <https://liberapay.com/yantar92>

Message #16 received at 59996-done <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: Ihor Radchenko <yantar92 <at> posteo.net>
Cc: 59996-done <at> debbugs.gnu.org
Subject: Re: bug#59996: 30.0.50; Overlays section of Elisp manual still
 states that overlays scale linearly
Date: Wed, 14 Dec 2022 20:15:28 +0200

> From: Ihor Radchenko <yantar92 <at> posteo.net>
> Cc: 59996-done <at> debbugs.gnu.org
> Date: Tue, 13 Dec 2022 10:42:17 +0000
> 
> Eli Zaretskii <eliz <at> gnu.org> writes:
> 
> > I guess that entire section should be audited for inaccuracies now;
> > reviews and patches are welcome.
> 
> Another part that requires update:
> 
> 
>        Emacs stores the overlays of each buffer in two lists, divided around
>     an arbitrary center position.  One list extends backwards through the
>     buffer from that center position, and the other extends forwards from
>     that center position.  The center position can be anywhere in the
>     buffer.
>     
>      -- Function: overlay-recenter pos
>          This function recenters the overlays of the current buffer around
>          position POS.  That makes overlay lookup faster for positions near
>          POS, but slower for positions far away from POS.
>     
>        A loop that scans the buffer forwards, creating overlays, can run
>     faster if you do ‘(overlay-recenter (point-max))’ first.
> 
>     
> ‘after-string’/‘before-string’ property description might mention that
> string are not displayed if the end/beginning of the overlay is not
> displayed for some reason.
> 
> Also, it might be worth highlighting that unlike text properties,
> overlays advance regardless whether insert or insert-and-inherit is used
> to insert the buffer text.

Fixed, thanks.

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