sub new {
	my ($pkg, $holes, $level) = @_;

	unless ( $holes ) {
		#
		# create the holes
		#
		my $holeLevel = 0;
		for ( my $i=0; $i<15; $i++ ) {
			if ( $i > 0 ) { $holeLevel = 1; }
			if ( $i > 2 ) { $holeLevel = 2; }
			if ( $i > 5 ) { $holeLevel = 3; }
			if ( $i > 9 ) { $holeLevel = 4; }
			#
			# the 5th hole is usaully has no peg initially.
			#
			$holes->[$i] = new hole( ( $i == 4 ) ? 'white' : 'black' , $i, $holeLevel );
		}

		#
		# link the holes
		#
		$holes->[0]->setLinks( [ $holes->[1], $holes->[2] ] );
		$holes->[1]->setLinks( [ $holes->[0], $holes->[2], $holes->[3], $holes->[4] ] );
		$holes->[2]->setLinks( [ $holes->[0], $holes->[1], $holes->[4], $holes->[5] ] );
		$holes->[3]->setLinks( [ $holes->[1], $holes->[4], $holes->[6], $holes->[7] ] );
		$holes->[4]->setLinks( [ $holes->[1], $holes->[2], $holes->[3], $holes->[5], $holes->[7], $holes->[8] ] );
		$holes->[5]->setLinks( [ $holes->[2], $holes->[4], $holes->[8], $holes->[9] ] );
		$holes->[6]->setLinks( [ $holes->[3], $holes->[7], $holes->[10], $holes->[11] ] );
		$holes->[7]->setLinks( [ $holes->[3], $holes->[4], $holes->[6], $holes->[8], $holes->[11], $holes->[12] ] );
		$holes->[8]->setLinks( [ $holes->[4], $holes->[5], $holes->[7], $holes->[9], $holes->[12], $holes->[13] ] );
		$holes->[9]->setLinks( [ $holes->[5], $holes->[8], $holes->[13], $holes->[14] ] );
		$holes->[10]->setLinks( [ $holes->[6], $holes->[11] ] );
		$holes->[11]->setLinks( [ $holes->[6], $holes->[7], $holes->[10], $holes->[12] ] );
		$holes->[12]->setLinks( [ $holes->[7], $holes->[8], $holes->[11], $holes->[13] ] );
		$holes->[13]->setLinks( [ $holes->[8], $holes->[9], $holes->[12], $holes->[14] ] );
		$holes->[14]->setLinks( [ $holes->[9], $holes->[13] ] );
	}
	my $obj = bless {
		holes	=> $holes, # ref to array of holes
		level	=> defined( $level ) ? $level : 0
	}, $pkg;
	return $obj;
}