use IO::All;
use JSON 'decode_json';

use constant ATTACK_PARAMS => [ qw/ type damage speed / ];

my $attack_types 
    = decode_json( io('attacks.json')->slurp );

foreach my $attack ( @$attack_types ) {

    exists $attack->{$_} or die "Malformed attack type: $_\n"
        for @{ATTACK_PARAMS()};

    my $name = "new_$attack->{type}";
    {
        no strict 'refs';
        *{$name} = sub { return shift->new(@{$attack}{ATTACK_PARAMS()}) };
    }

}