I like this a lot, and I'm using it tomorrow (well, Monday). I often want to do this, but I also quite often want to have the flexibility to call the sub with either a hash or an array - for example when I have a sub which sometimes gets by on just one argument, or sometimes needs a whole load of stuff specified. So I favour the following tweak-ette (which I agree is making a boldish assumption that the user wd have to be aware of, namely that if *all* the named args are missing, that's not because we completely ballsed it up, but because we're submitting an array).

    *{$sub} = sub {
        my %args = $wrapper{ hashref } ? %{$_[0]} : @_;
        my @orig_args;
        my @missing_args;
        foreach my $arg_name ( @{$wrapper{ names }} ) {
            if ( exists $args{ $arg_name } ) {
                push @orig_args, $args{ $arg_name };
            } elsif ( exists $wrapper{ default }{ $arg_name } ) {
                push @orig_args, $wrapper{ default }{ $arg_name };
            } else {
                push @missing_args, $arg_name;
            }
        }
        if (@missing_args == 0) {
            return $orig_sub->( @orig_args );
        }
        elsif (@missing_args == @{$wrapper{ names }}) {
            return $orig_sub->( @_ );
        }
        else {
            croak("Cannot find value or default for arg(s) '" . (join 
+"', ", @missing_args) . "'");
        }
    }
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My only other observation is that it raises a "Subroutine redifined" warning - my grasp of name space issues is too weak to know whether that can be avoided. But I must say, I like it.

§ George Sherston