Re: bug#17453: Isearch doesn't work properly with Follow Mode.

[Eli Zaretskii <eliz@gnu.org>]

> Date: Sun, 1 Nov 2015 13:52:53 +0000
> From: Alan Mackenzie <acm@muc.de>
> Cc: emacs-devel <emacs-devel@gnu.org>
> 
> No problem!  The patch below doesn't actually apply at the moment, due
> to some (?very) recent change in isearch.el.  But it wouldn't run
> anyway, because window*-start and friends aren't there yet.
> 
> 
> 
> diff --git a/lisp/isearch.el b/lisp/isearch.el
> index 4fc9b38..07ec534 100644
> --- a/lisp/isearch.el
> +++ b/lisp/isearch.el

How is this "not having isearch know about Follow mode"?  I see that
knowledge on every step of this patch, whenever you call the new
functions.

So maybe I'm missing something, but I really don't see why this
variant is significantly better than the one Stefan didn't like.  Can
you explain what am I missing here?

I thought you will come up with some more generic framework for
commands to "scroll" the display by switching to the next window (when
under Follow mode), if possible.  But unless I'm missing something
very important, this isn't that framework, is it?

Btw, I see no reason to introduce new functions.  Instead, we could
have the original ones accept an additional optional argument.

As yet another comment, wrt this exchange between you and John:

> > What is the reason for having separate functions such as window*-start,
> > instead of just taking the car of a list of windows?  I may be missing some
> > context here, but this sounds like special-casing general behavior, and I'm
> > wondering why it's necessary...
> [...]
> The fact that the "group" of windows is represented by a list is an
> implementation detail to be encapsulated within follow.el.  In the
> (fairly distant) future, this might perhaps be superseded by code in
> redisplay.  Perhaps.

You are right about not relying on the list, but window-next-sibling
and window-prev-sibling are available, and always will be, so you can
"trivially" use them instead of relying on a list.  If you agree, then
John's question still stands, I think.