use strict ;
use warnings ;
use Data::Dumper ;

my @limit = (reverse 1..5) ;
my $limit = { _l => \@limit } ;
bless ( $limit, 'limit' ) ;
sub countdown {
	my $val = shift ;
	my $iter = sub {
		if ( $val-- ) {
			$_[0] = $val ;
			return 1 ;
		}
		return ;
	} ;
	return $iter ;
}
while ( my $iter = $limit->Next( *countdown ) ) {
	while ( $iter->( my $a ) ) {
		print "$a: " ;
	}
	print "\n" ;
}

package limit ;
use strict ;
use warnings ;
use Data::Dumper ;
sub Next {
	my $this = shift ;
	if ( @{$this->{_l}} ) {
		return $_[0]->( shift @{$this->{_l}} ) ;
	}
	return ;
} ;