Re: Default value of recenter-redisplay

[Bob Proulx <bob@proulx.com>]

Eli Zaretskii wrote:
> > John Shahid wrote:
> > I'm wondering why the default value of the variable is set to `tty' ?
> 
> Because one important interactive use of 'recenter' is to redraw the
> screen to eliminate display corruptions due to all kinds of unrelated
> messages being dumped on the console.  When this variable and the
> related feature was introduced, RMS explicitly asked not to change the
> then default behavior on TTY's, see
> 
>   http://lists.gnu.org/archive/html/emacs-devel/2009-06/msg00416.html

I am compelled to say (because otherwise someone will argue that no
one complained about the change) that even if other people don't ever
see output emitted to their tty outside of emacs that I do still
routinely run into the case.  I see shutdown warnings or kernel
messages from martian IP packets or whatwever as there are many things
that write to the tty.  I rely upon C-l a lot.

Obviously a graphical X11 window does not have external processes
modifying it and does not need to be redisplayed.

> > Also, is it safe to set the variable to `nil' ?
> 
> If you don't care about fixing corrupted display on TTYs (or never
> experienced that), you can safely change it to nil.
> 
> > If it is safe, can we change the default value to `nil' in order to
> > have a better terminal experience ?

A better terminal experience is that C-l can be used after several
lines have been written to the tty by outside processes.  Keeping it
the same as with other terminal programs such as bash, vi, vim, less,
mutt, and so forth.  Making C-l work differently from those other
programs makes for a worse terminal experience.  A positive transfer
of learning across many programs.

> Why does it have to change by default?  I generally find arguments
> about default values to be waste of time and energy, since anyone who
> doesn't like the default can change it for them.

Changing defaults is painful and frustrating to people (often me) who
make use of the defaults.  It makes the feature one that is required
to be configured before it can be used.  Which contributes to making
emacs hard to learn for newcomers.  Which perpetuates the stereotype
that emacs is too arcane.  That's bad.

And as long as I am here I am also one of those people who didn't like
the change from recenter to recenter-top-bottom.  I added this to my
key bindings to avoid it.

  (global-set-key "\C-l" 'recenter) ; originally recenter, now annoyingly recenter-top-bottom

Bob