>perl -le"print sprintf '%2$s %1$s', qw( a b )"
b a

##</code><code>##

$hello = "Hello $name";

##</code><code>##

use String::Interpolate qw( );

sub format {
   my ($pat, $args) = @_;
   my $t = String::Interpolate->new($args);
   $t->($pat);
   return "$t";
}

my $hello = format('Hello $name', { name => 'World' });