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From: les@chinet.chi.il.us (Leslie Mikesell)
Newsgroups: comp.editors
Subject: Re: Vi/Ex: Editor command line editor?
Message-ID: <1991Mar01.171956.6466@chinet.chi.il.us>
Date: 1 Mar 91 17:19:56 GMT
References: <5104@lure.latrobe.edu.au> <2608@virgo.csl.sony.co.jp>
Organization: Chinet - Chicago Public Access UNIX
Lines: 43

In article <2608@virgo.csl.sony.co.jp> kono@csl.sony.co.jp writes:

>>  :.,.+3s/some long expression/another long expression/g...
>>    OOPS!  I mistyped something.
>>Command line editing for ex?

>In vi, my friends gave me this. (Yes, I prefer vi, even in non crt terminal..)
>map ^X "zdd@z
>map! ^X "zdd@z
>Of course ^X means real control-X. Input your complex :command, and
>^X will delete it and execute it.

Using this macro without understanding it would obscure the real value
of the technique, so let me elaborate on what this does and why it
is a good idea to use it for anything complicated.

The idea here is to build the complicated command in the edit buffer,
delete it to a named register, then execute the register.  Aside from
the advantage of being able to use all normal edit command while typing
the entry, you can examine the results after execution and if you
didn't get it quite right, simply 'u' to undo the command, yank the
command back to the edit buffer and try again.  The vi commands to
do this are simple enough that it's hardly worth mapping:

(I'll use register a here - any letter will do)  
"add  (delete line to register)
@a    (execute register)
u     (didn't work, undo it *note - must be NEXT edit command)
"aP   (put register a back into edit buffer)

Knowing this makes life much easier for those of us who never get it
right on the first try.  Note that you have to include the ":" to
begin an ex mode command and double any ^V quoting needed (once to
get it into the edit buffer and another copy for when the command
is evaluated.

Note for anyone developing a new editor or working on new features
for old ones.  Being able to yank the last (or last n) command(s)
into the edit buffer so that you could start this cycle after the
undo is right at the top of my wish list.

Les Mikesell
  les@chinet.chi.il