package Number;

use strict;
use warnings;
use IO::File;
use Fcntl ':flock'; 
use Cwd;

sub new{
        my $class = shift;
        my $self = bless{}, $class;
        return eval{
                my $file = $class.".pm";
                $self->{POS} = tell DATA;
                $self->{BUF} = '';
                read DATA, $self->{BUF}, 32;
                $self->{NR} = unpack "A32", $self->{BUF};
                $self->{FH} = new IO::File;
                my $dir = getcwd();
                $self->{FH}->open("$dir/$file", O_RDWR) or die "IO-Error: $!";
                flock $self->{FH}, LOCK_EX or warn "Your system does not support flock";
                $self;
        };
}

sub nr{
        my $self = shift;
        return $self->{NR}++;
}

sub DESTROY{
        my $self = shift;
        $self->{FH}->seek($self->{POS}, 0);
        $self->{FH}->print(pack "A32", $self->{NR});
}

1;
__DATA__
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