bug#12811: 24.3.50; `scroll-up/down-aggressively' don't seem to work as expected

[Eli Zaretskii]

> Date: Tue, 6 Nov 2012 20:18:30 +0100
> From: Dani Moncayo <dmoncayo@gmail.com>
> Cc: 12811@debbugs.gnu.org
> 
> So I'd like to make this request:
> * Make obsolete the variables `scroll-up/down-aggressively'.
> * Extend the semantics of the variable `scroll-step' to accept also a
> fractional number between 0 and 1, so that for example 0.7 would mean:
> "when point moves out, try to get it back into view by scrolling
> up/down an amount equal to the 70% of the height of the window.  If
> that fails, center in the window the line where point is".

Wouldn't this keep the same semantics, but in one variable instead of
3?

Anyway, it's too late to make such changes now, because a year and a
half so ago, there a was similar discussion about
scroll-conservatively, and people who set it to a large value
explicitly asked for that to work over large scrolls.  So the code was
restructured to support that (that's why it was so easy for me to fix
this one); going back means a serious surgery on that code, which I
think is unjustified at this point, as I didn't hear any complaints
about scrolling for a long time.

> It would not make sense, indeed, but according to the current
> documentation, point should be positioned according to
> `scroll-up/down-aggressively'.

Well, now it does.

> > That is why what you expected never worked in Emacs, at least since
> > v21.1.  The code which implements the effect of these variables was
> > written under the assumption that point is only a small ways outside
> > of the window, one or 2 screen lines, because this is what happens
> > when you type "C-n" or "C-p" on the border of the scroll margin.
> 
> But that assumption is false in many real-life cases.

Not when you cause the scroll with C-n or C-p (without numeric
arguments).  Then it's true.

> > Having said that, since the code already almost did TRT, it is much
> > easier for me to fix it for this use case than to argue about the
> > applicability of these variables.  So I did just that in revision
> > 110795 on the emacs-24 branch.
> 
> Good, thanks.  Then perhaps the documentation should be updated to
> reflect this, no?

What's wrong with the documentation now?  The code does what it says,
no?