From: Leon Theremin <thephist@...>
Date: 2010-05-08T08:49:30+09:00
Subject: Modify Class Instance Inside Another Class (scope problem?)

First, I've not used a forum before, but I want to be more involved.
Please excuse (and correct) poor etiquette.

The context for what I'm really trying to do is that I want to make card
games. I have general purpose classes for "card" objects (Card, Deck,
Shoe). And I have game specific classes, which may need to modify
attributes of the card objects. For example, each card has 'suit',
'rank', and 'value' - the 'value' of Jack in Black Jack is 10, but in
solitaire it's 11.

I've created this simplified version of the code to focus on this
problem.

Problem: Game.cards is the same before and after Game.assign_values (no
values assigned).

My questions are:
1. Why doesn't this work the way I'm trying to do it?
2. Should I be using a different approach?

class Card
  attr_accessor :name, :value
  def initialize(name)
    @name = name
    @value = nil
  end
end

class Game
  attr_accessor :cards
  NAMES = ['a','b','c','d']
  NAME_VALUES = { 'a' => 1,'b' => 2,'c' => 3,'d' => 4 }
  def initialize
    @cards= self.cards
  end

  def cards
    cards = []
    NAMES.each do |n|
      card = Card.new(n)
      cards << card
    end
    cards
  end

  def assign_values
    @cards.each do |card|
      name = card.name
      value = NAME_VALUES[name]
      card.value = value
    end
  end
end

g = Game.new
p g.cards
g.assign_values
p g.cards
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