Re: Is there any particular reason `scroll-other-window' is written in C and not in ELisp?

[Eli Zaretskii <eliz@gnu.org>]

> From: Marcin Borkowski <mbork@mbork.pl>
> Cc: Emacs-devel@gnu.org
> Date: Tue, 29 Dec 2015 18:37:40 +0100
> 
> > Because it needs to determine the new window-start which is a
> > window-full above or below the current one, without assuming that all
> > the lines have the same height in pixels.  How do you do that in Lisp?
> > (The current implementation simulates display.)
> 
> Interesting, though I know too little about Emacs internals to fully
> understand your answer.  I thought it just does something like
> 
> (save-excursion
>   (other-buffer)
>   (scroll-up))
> 
> Why my (probably naïve) implementation won't work?

(You forget other-window-for-scrolling, but that's beside the point.)

How would that help?  The guts are in scroll-up, which is in C (as all
the scrolling commands).

Or are you saying that the bug is in the other-buffer part, rather
than in the scrolling part?

> > Sounds like a bug that should be reported.  Not sure if it's in core
> > Emacs or not, but please do report it with all the necessary details
> > to whatever the guilty parties are.
> 
> Not Emacs core, you're right.  I'll file a bug report.

Thanks.