package Tie::Match;
use strict;

sub TIESCALAR {
    my ($class, $regex) = @_;
    return bless [undef, $regex], $class;
}

sub STORE {
    my ($self, $new) = @_;
    $self->[0] = $new =~ $self->[1] ? $new : undef;
}

sub FETCH {
    my ($self) = @_;
    return $_->[0];
}

sub UNTIE   { }
sub DESTROY { }

__END__

=head1 NAME

Tie::Match - Tie a scalar that is undef when not matching a regex

=head1 SYNOPSIS

    tie my $scalar, 'Tie::Match', qr/^[1-5]+$/;
    while ($scalar = <>) {
        if (defined $scalar) {
            print "Match: $scalar\n";
        } else {
            print "No match.\n";
        }
    }

=head1 DESCRIPTION

Ties a scalar. The scalar can be set, but will be undef if the
new value does not match the given regex.

=head1 URL

http://perlmonks.org/?node_id=157404

=cut