use strict;
use warnings;

sub stringmaker {
	my( $start, $stringref ) = @_;
	return sub { $start.$$stringref }
}

my $r = 300;
my $g = stringmaker( 'g', \$r );
print $g->()."\n"; #would be 'g300', that's ok
$r = 500;
print $g->()."\n"; #would be 'g500'