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RE: bug#736: C-l interacts badly with scroll-conservatively
From: |
Drew Adams |
Subject: |
RE: bug#736: C-l interacts badly with scroll-conservatively |
Date: |
Sun, 17 Aug 2008 13:14:22 -0700 |
> >> emacs -q
> >> M-: (setq scroll-conservatively 100) RET
> >> C-h n
> >> C-v
> >> C-l
> >> C-l
> >> C-l
> >>
> >> The repeated C-l's don't move to the top or bottom of the
> >> window, unlike the usual behavior (new to Emacs 23) of
> >> recenter-top-bottom.
> >
> > Maybe I'm misunderstanding the bug report, but by design
> > `scroll-conservatively' modifies the behavior of
> > `recenter-top-bottom'. As the doc string says:
> >
> > "Top and bottom destinations are actually
> > `scroll-conservatively' lines from true window top
> > and bottom."
>
> That's true; I didn't see that.
>
> But why does recenter-top-bottom use scroll-conservatively? AFAICT,
> people often use a large nonzero number for scroll-conservatively so
> that when point is at the bottom of the window, C-n scrolls
> down by one
> and keeps the cursor at the bottom; and similarly, if point is at the
> top of the window, C-p keeps the cursor at the top. It doesn't make
> sense to make scroll-conservatively affect C-l.
>
> I think we should use scroll-margin for this purpose, rather than
> scroll-conservatively.
>
> What do people think?
I believe this (below) was the last message in the thread that discussed this.
AFAIK, nothing was decided about using a different user option or rationalizing
the various uses and doc for `scroll-conservatively'.
---------------8<---------------------------
> From: Drew Adams Sent: Saturday, December 01, 2007 8:54 PM
> To: address@hidden Subject: RE: recenter-top-bottom
>
> > the doc string of scroll-step says this:
> >
> > "If you want scrolling to always be a line at a time,
> > you should set `scroll-conservatively' to a large
> > value rather than set this to 1."
>
> Where "this" refers to `scroll-step', not
> `scroll-conservatively', presumably. That could be made
> clearer, BTW. And "a large value" could be made clearer also:
> example? What's large?
>
> > When scroll-conservatively is changed, it's usually for
> > this reason, I think. (See Richard's explanation.)
>
> 1. Then change the `recenter-top-bottom' code to use a new
> user option, or some other existing option that is more
> appropriate than `scroll-conservatively'.
>
> 2. FWIW, the manual, the `scroll-step' doc string, and
> Richard seem to be saying different things. The manual
> (Emacs, node Auto Scrolling) says that you can use "a small
> number" for `scroll-conservatively' to scroll "the text just
> far enough to bring point back on screen". The doc string of
> `scroll-step' says that you can use "a large value" for
> `scroll-conservatively' to scroll "a line at a time". Those
> can both be true, but they would seem to be different uses of
> the option.
>
> Richard says that he sets `scroll-conservatively' to a large
> value to "bring point onto the screen by scrolling, with even
> one line of overlap". That doesn't seem to be the same thing
> as scrolling "a line at a time".
>
> I'm not saying that anyone is wrong or that the doc should be
> changed (I don't know). And I'm no longer claiming that
> `scroll-conservatively' is appropriate for
> `recenter-top-bottom' (use some other option, if you like).
> I'm saying only that the uses or interpretations of
> `scroll-conservatively' seem various.