package Attack {
    use Moo;
    use Types::Standard qw( Str Int );

    has type  =>  ( is => 'ro', isa => Str );
    has damage => ( is => 'ro', isa => Int );
    has speed  => ( is => 'ro', isa => Int );
}

##</code><code>##

    sub light {
        my $self = shift;
        return $self->new(
            type   => 'light',
            damage => '1',
            speed  => '5',
        );
    }

    sub fast {
        my $self = shift;
        return $self->new(
            type   => 'light',
            damage => '1',
            speed  => '7',
        );
    }

    sub heavy {
        my $self = shift;
        return $self->new(
            type   => 'heavy',
            damage => '2',
            speed  => '4',
        );
    }


##</code><code>##

    sub BUILDARGS {
        my ($self, @args) = @_;
        if ($args[0] eq 'heavy') {
            return {
                type   => 'heavy',
                damage => '2',
                speed  => '4',
            };
        }
        # same for 'light' and 'fast' of course
        else {
            return { @args };
        }
    }

##</code><code>##

my $att1 = Attack->heavy;

##</code><code>##

my $att2 = Attack->new('heavy');