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	sedalia.sinet.slb.com
Reply-To: vons@cesar.crbca1.sinet.slb.com
Subject: Something for the FAQ ?
Date:	Tue, 14 Sep 1993 05:56:23 -0400


Hello all,

I was just wondering, is there a collection of useful functions somewhere?
I found some in the FAQ and in the mail list archive of course, but I
assume that there are a lot more useful things out there, which could
be made more accessible when added to the FAQ for example. What made me
think of this is the following:


I'm using the prompt function for the initialisation of interactive
subshells, but this makes $status unusable if you aren't careful.
I came up with the following, which seems to work nicely. (init
is a function to initialise the subshell).

fn prompt  {
    s=$status {
        if ( ! ~ $ipid $pid ) {
            ipid=$pid

            # one time call to init_shell(), initialises interactive subshell
            init_shell
        }
        return $s
    }
}

You can't simply save&restore $status, since the assignment to $status
itself would change the status.


I also wrote the next functions in order to be able
to clean up my $path (removing duplicates), or to remove an entry.

# remove(varname, elt) removes elt from $varname
fn remove {
    vn=$1 e=$2  o=() *=$$vn{
        while( ! ~ $#* 0)
       {
           ~ $*(1) $e || o=($o $*(1) )
           shift
       }
       $vn=$o
    }
}

# clean(varname) removes all double entries from $varname, keeping the first
fn clean {
    vn=$1 o=() *=$$vn{
        while( ! ~ $#* 0)
        {
            ~ $o $*(1) || o=($o $*(1) )
            shift
        }
        $vn=$o
    }
}

# example
clean path
remove path /usr/bin

The only thing to add is the support for ':' separated lists,
like MANPATH,FONTPATH,HELPPATH,LD_LIBRARY_PATH which don't have a
list-equivalent like PATH/path.


Thought it might be useful to have this kind of stuff in a place where
it can easily be found, like the FAQ for example.


	Gert-Jan

---------------------------------------------------
J.G. Vons   E-Mail: vons@cesar.crbca1.sinet.slb.com