Path: utzoo!attcan!uunet!tut.cis.ohio-state.edu!att!cbnews!smk
From: smk@cbnews.att.com (Stephen M. Kennedy)
Newsgroups: comp.editors
Subject: Re: Another bug in vi ?
Summary: vi feature
Message-ID: <1990Oct3.150431.19010@cbnews.att.com>
Date: 3 Oct 90 15:04:31 GMT
References: <896@pcsbst.pcs.com>
Organization: AT&T Bell Laboratories
Lines: 35

In article <896@pcsbst.pcs.com>, wd@samsa.pcs.com (wd) writes:
> If I define
> 
> 	:map! #a foo
> 
> and type "#a" while in insert mode, my version of vi appends some
> garbage after inserting "foo"  (usually it looks like "fooa", but
> I have seen "fooli" and other garbage, too). This happens only if
> the first character of the mapped pattern is a '#'.   It does not
> depend on the rest of the pattern.

Believe it or not, this is a vi (mis?)feature.  A lhs of '#a' means
function key 'a' to vi.  Yes, even though you probably don't have a
function key 'a'; a more common usage is '#1' for function key 1, etc.  In
insert/replace/append mode, vi seems to expect function keys to map to a rhs
that does an <ESC> to go into command mode and then does cursor positioning
commands.  Vi then endeavors to put you back into insert/replace/append mode
at the right spot with the appropriate 'a', 'i', 'li', etc. commands.  Your
"function key" definition doesn't follow this <ahem> undocumented protocol,
so you get the trailing 'a' or 'li' garbage because you never left
insert mode in the first place.  Vi predefines mappings for the up, down,
left, right, and home function keys for most terminals.  I'm not sure I 
see the utility of this kind of cursor positioning within i/r/a mode;
perhaps for editing a table in replace mode?

Workarounds?

	- Don't use # as the first character of the lhs.
	- End rhs with <ESC> (gak) (I didn't try this either)

Steve Kennedy
smk@cbosgd.att.com

> Company : PCS GmbH, Pfaelzer-Wald-Str. 36, 8000 Munich W-Germany.
Congratulations!  I hope it works out for you.