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From: flee@gondor.psu.edu (Felix Lee)
Newsgroups: comp.unix.wizards,comp.unix.questions
Subject: xn/xenl as told by SVID (Re: Termcap/terminfo)
Message-ID: <3088@psuvax1.psu.edu>
Date: Sun, 15-Nov-87 03:31:54 EST
Article-I.D.: psuvax1.3088
Posted: Sun Nov 15 03:31:54 1987
Date-Received: Sun, 15-Nov-87 22:41:59 EST
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In article <9290@mimsy.UUCP> chris@mimsy.UUCP (Chris Torek) writes:
> Perhaps terminfo defines this better.  In termcap, unfortunately,
> `xn' does not describe cursor positioning when a character is
> printed at the end of a line.
No, terminfo says nothing about cursor position.  It does explicitly
say that xenl denotes both the eat-newline-glitch and magic-wrap.

In the presence of xenl, you should probably lose the cursor position
when you bang past the right margin:  use absolute cursor addressing
if you must move from that indeterminate position between lines.

> I wanted to be able to write the last character of each line,
> including the last line.
Writing to the lower right corner without scrolling is not guaranteed
with xenl (maybe we need a boolean can-write-lower-right).  Without
that guarantee, I can think of a number of ways of writing in the
lower-right corner, all more trouble than it's worth (scroll regions,
insert line, insert character).  It's much easier to avoid the problem
altogether.

> (If anyone cares, my Window Library assumes that `xn' describes
> the terminal with the virtual column.  The code *is* 5 years old:
> I know better now, but have not the time to fix it.)
GNU Emacs also thinks xn describes only magic-wrap.
--
Felix Lee	flee@gondor.psu.edu	{cbosgd,cmcl2}!psuvax1!gondor!flee