Re: [vile] Limitations of :g commands

[Thomas Dickey]

On Wed, 10 May 2006, Paul Fox wrote:

> decklin wrote:
> > Today (okay, so I only installed vile yesterday) I found myself needing
> > to do something with every other line in a file.  In vi, the rhs of :g
> > is just an ex command, so this can be done in a not-very-pretty way by
> > specifiying a relative range, like
> >
> > :g/^/+d
...
> > Sorry if this has been asked before; all I could find were the new
> > list's archives.
>
> i don't recall this coming up before.

Perhaps not on the mailing list, but I recall the general topic coming up. 
It's doable, but not trivial.  The problem is that vile's splitting the 
command-parsing into parts and has only a simple parser for the command at 
the point where it encounters the "+d".  The "+" is part of an address 
expression and vile's expecting only a verb.

What makes it nontrivial to implement is how to handle line-editing (and 
the corresponding command-history), since addresses are parsed in one 
place and verbs in another.  The execute_named_command() function in 
exec.c does something like that (and it took quite a while to debug).

Perhaps it would be possible to make that function reentrant, so it could 
be used to process arbitrary ex-commands...

--
Thomas E. Dickey
http://invisible-island.net
ftp://invisible-island.net