#! /usr/bin/perl -w

use strict;

sub make_gen {
    my $num = shift;
    sub { sprintf '%09s', $num++ }
};

my $g1 = make_gen( 1 );
print $g1->(), "\n", $g1->(), "\n\n";

my $g2 = make_gen( 'zzx' );
print $g2->(), "\n" for 1..4;

__END__
output:
000000001
000000002

000000zzx
000000zzy
000000zzz
00000aaaa