From: "Jesús Gabriel y Galán" <jgabrielygalan@...>
Date: 2012-07-18T21:20:24+09:00
Subject: Re: learning by doing part 2 - tc game

On Wed, Jul 18, 2012 at 2:02 PM, Sebastjan H. <lists@ruby-forum.com> wrote:
> I need (hopefully) one final help for this game:)
>
> I am trying to program the battle turn and I just wanted to know whether
> there is any better or more elegant solution other than branching so
> much:
>
> -------------------------------------------------------------
>   ## Here it needs to branch according to card attributes: spells don't
> have attacks.
>   if card.type == "armor_spell"
>     player_hp = player_hp + card.armor
>
>   elsif card.type == "healing_spell"
>     player_hp = player_hp + card.heal
>
>   elsif card.type == "debuff_spell"
>     if ai_card.type == "dragon" or ai_card.type == "dire wolf"
>       ai_card.attack = ai_card.attack - card.debuff
>     end
>
>   elsif card.type == "dragon" or card.type == "dire wolf"
>     if ai_card.type == "dragon" or ai_card.type == "dire wolf"
>     player_hp = player_hp + card.armor - ai_card.attack
>     puts "#{ai_card.name} strikes with " + ai_card.attack.to_s
>     puts "\n"
>
>   end
>
>   if ai_card.type == "armor_spell"
>     ai_hp = ai_hp + ai_card.armor
>
>   elsif ai_card.type == "healing_spell"
>     ai_hp = ai_hp + ai_card.heal
>
>   elsif ai_card.type == "debuff_spell"
>     if card.type == "dragon" or card.type == "dire wolf"
>       card.attack = card.attack - ai_card.debuff
>     end
>
>   elsif ai_card.type == "dragon" or ai_card.type == "dire wolf"
>   ai_hp = ai_hp + ai_card.armor - card.attack
>   puts "#{card.name} strikes with: " + card.attack.to_s
>   end
>
>
>   @deck.delete(card)
>   @ai_deck.delete(ai_card)
>   puts "Player health is #{player_hp}."
>   puts "Ai health is #{ai_hp}."
> -------------------------------------------------------------
> thank you very much.


One approach that implies a huge refactor of your datastructures,
would be to have each card object implement its own logic on the game
state:

class ArmorCard
  attr_reader :armor_level
  def initialize armor
    @armor_level = armor
  end

  def perform_action game_state
    game_state.increment_player_hp(armor)
  end
end

class HealingSpellCard
  attr_reader :spell_level
  def initialize spell_level
    @spell_level = spell_level
  end

  def perform_action game_state
    game_state.increment_player_hp(spell_level * 2) #healing spells
heal double their level (example of spell logic)
  end
end

Then you only need to call the perform_action method in each card
object. If you have common logic, such as attack card only differing
in name and attack value, but the attack logic is the same, then you
could model it with a class hierarchy:

class Card
  def is_attack?
    false
  end
end

class AttackCard < Card
  def is_attack?
    true
  end

  def perform_action game_state
    game_state.increment_player_hp(armor)
    if game_state.ai_card.is_attack?
      game_state.increment_player_hp(-ai_card.attack)
    end
  end
end

class Dragon < AttackCard
  attr_reader :armor, :attack
  def initialize armor, attack
    @armor = armor
    @attack = attack
  end
end

And so on. You might have different classes depending on
characteristics or other ways to model it: maybe AttackCard,
SpellCard, etc could be modules you mixin in specific cards, for
example if some card can be both. Then maybe you could have a general
implementation of perform_action in the Card class. It depends.

I hope this gives you some ideas.

Jesus.