Re: cmd line like switches for functions and operators.

[Luke Palmer]

Juerd writes:
> Michele Dondi skribis 2004-06-22 18:24 (+0200):
> >   rename -v => 1, $orig, $new;
> 
> Any specific reason for the minus there? Perl's not a shell (yet).
> 
> >   rename.SWITCHES{-v} = sub {
> >       my ($o, $n) = @_;
> >       print "renaming `$o' to `$n'\n";
> >   }
> 
> I think just using named arguments would be better and much easier.
> 
> sub rename ($old, $new, +$verbose) {
>     say "Renaming '$old' to '$new'" if $verbose;
>     ...;
> }
> 
> rename verbose => 1, $oldthingy, $newthingy;

That one doesn't work.  Named arguments have to come at the end of the
parameter list (just before the "data list", if there is one).  This is
a decision I'm gradually beginning to disagree with, because of:

    sub repeat (&code, +$times = Inf) {
        code() for 1..$times;
    }

This is a plausable routine.  Now look how it's called:

    repeat {
        print "I'm ";
        print "doing ";
        print "stuff\n";
    } :times(4);

This is a horrid violation of the end weight principle.  Much nicer is
the illegal:

    repeat :times(4) {
        print "I'm ";
        print "doing ";
        print "stuff\n";
    }

Luke

> rename $oldthingy, $newthingy, :verbose;  # alternative, more
>                                           # switch-like pair constructor
> 
> 
> Juerd