delay argument interpretation

delay argument interpretation

[Paul Lew]

I have a shell function 'ask' to aid the interactive command
execution, for example,

	function ask {
		echo -n "$*? [y/n]: "
		read yon
		if [[ "$yon" = "y" ]]; then
			$@
			echo "end of: $@"
			fi
		}

Then I can use commands similar to the one below to interactively
select the desired candidates:

	for i in *.c; do
		ask diff old/$i $i
		done

will work like:

	diff old/a.c a.c? [y/n]: 
	diff old/b.c b.c? [y/n]: 
	diff old/c.c c.c? [y/n]: 

This all work out nice, however, the comment blocks in these files are
different and I would like to apply a filter (rmcmt in the example
below) to it so I will only see the source differences:

	for i in *.c; do
		ask diff =(rmcmt old/$i) =(rmcmt $i)
		done

However the =(...) expanded info a temporary filename and the prompt
became:

	diff /tmp/zshaaqqxa /tmp/zshaaqqxb? [y/n]:
	diff /tmp/zshaaqqxa /tmp/zshaaqqxb? [y/n]:
	diff /tmp/zshaaqqxa /tmp/zshaaqqxb? [y/n]:

What can I do to quote the arguments so it will not expand until
later in function ask?  Any help will be appreciated...

Re: delay argument interpretation

[Andrew Main]

function ask {
  local yon
  echo -n - >&2 "$1? [y/n]: "
  read yon
  [[ "$yon" == [yY]* ]] && eval "$1"
}

for i in *.c; do
  ask 'diff =(rmcmt old/$i) =(rmcmt $i) # $i = '$i
done

There are other obvious variations.

-zefram

Re: delay argument interpretation

[Bart Schaefer]

On Jul 21, 12:05pm, Paul Lew wrote:
} Subject: delay argument interpretation
}
} This all work out nice, however, the comment blocks in these files are
} different and I would like to apply a filter (rmcmt in the example
} below) to it so I will only see the source differences:
} 
} 	for i in *.c; do
} 		ask diff =(rmcmt old/$i) =(rmcmt $i)
} 		done

The obvious solution to this specific problem is to use "diff -I <re>" to
ignore lines matching the regular expression <re>.

The other solution that occurs to me is

	function diffsrc() {
	    local x=$[$#-2]
	    diff $*[1,$x] =(rmcmt $*[$x+1]) =(rmcmt $*[$x+2])
	}

	for i in *.c; do ask diffsrc old/$i $i; done

} What can I do to quote the arguments so it will not expand until
} later in function ask?

Something like what Zefram suggested is the only way; really do quote them
yourself.  In csh I'd use an alias with \!: expansions like this:

	alias ask 'echo -n \!*:q"? [y/n] "; askify \!*'

(and then "askify" would be a script that does everything but the echo in
your "ask").  But zsh doesn't have such a mechanism for re-quoting the
command line at alias time, before any of it gets expanded.  The closest
you can get is somthing like

	alias ask='noglob ask'

which delays filename expansion but not command name substitution et. al.
I have this little function:

    show () {
        show=() 
        show=($~*) 
        print -rc $show
    }
    alias show='noglob show'

which allows me to do things like

	show **/*.{orig,rej}
    (examine what I see for a bit, then do something else like)
	rm $show
    (which avoids doing the recursive glob twice).

My only complaint about this is that completion for "noglob" gets invoked
if I happen to press TAB, rather than completion for "show".  I think
that's a bug.

-- 
Bart Schaefer                                 Brass Lantern Enterprises
http://www.well.com/user/barts              http://www.brasslantern.com

Re: delay argument interpretation

[Andrew Main]

Bart Schaefer wrote:
>    show () {
>        show=() 
>        show=($~*) 
>        print -rc $show
>    }
>    alias show='noglob show'

Why?  What's wrong with

function show {
  show=("$@")
  print -rc -- "$@"
}

-zefram

Re: delay argument interpretation

[Bart Schaefer]

On Jul 22,  9:23am, Andrew Main wrote:
> Subject: Re: delay argument interpretation
>
> Bart Schaefer wrote:
> >    show () {
> >        show=() 
> >        show=($~*) 
> >        print -rc $show
> >    }
> >    alias show='noglob show'
> 
> Why?  What's wrong with
> 
> function show {
>   show=("$@")
>   print -rc -- "$@"
> }

The latter fails to set $show to empty when the pattern doesn't match
anything.  I have nomatch set, so if there's a globbing failure in the
arg list, "show" never executes.  I want to force "show" to start, and
*then* get the globbing failure.

-- 
Bart Schaefer                                 Brass Lantern Enterprises
http://www.well.com/user/barts              http://www.brasslantern.com

Re: delay argument interpretation

[Zoltan T. Hidvegi]

Bart Schaefer wrote:
> The latter fails to set $show to empty when the pattern doesn't match
> anything.  I have nomatch set, so if there's a globbing failure in the
> arg list, "show" never executes.  I want to force "show" to start, and
> *then* get the globbing failure.

Alias show to noglob show.

Zoli

Re: delay argument interpretation

[Zoltan T. Hidvegi]

hzoli wrote:
> > The latter fails to set $show to empty when the pattern doesn't match
> > anything.  I have nomatch set, so if there's a globbing failure in the
> > arg list, "show" never executes.  I want to force "show" to start, and
> > *then* get the globbing failure.
>
> Alias show to noglob show.

Oh, I did not read the beginning of the mail.  Sorry for my ignorance.

Zoltan