my $template = "Hi %foo, I have a %bar.\n";

print fill($template, foo => 'mickey', bar => 'robot');

sub fill {
    my $template = shift;
    my %params = @_;
    $template =~ s/%([a-z]+)/$params{$1}/g;
    return $template;
}

##</code><code>##

my ($x, $y, $z);
my $callback = sub { print $x, $y, $z, "\n" };

($x, $y, $z) = (1, 2, 3);
$callback->();

($x, $y, $z) = (4, 5, 6);
$callback->();

##</code><code>##

my $callback = sub {
    my ($x, $y, $z) = @_;
    print $x, $y, $z, "\n";
};

$callback->(1,2,3);
$callback->(4,5,6);