From: Jeroen Lodewijks <lists@...>
Date: 2012-09-19T23:29:54+09:00
Subject: Re: Class variables

Thanks for the answer.

The problem with this code is that this variable is accessible from 
outside.
Let me elaborate what I tried to do. I have code like this:
(Not saying this good code, I a messing around at the moment)

class Card
  attr_accessor :suit
  attr_accessor :value
  attr_accessor :name
  attr_accessor :picture
  attr_accessor :hcp

  def new(value, suit)
    @value = value
    @suit = suit
  end

  def hcp()
    return @hcp
  end
end

class Deck
  require '.\Card'
  @deck = []
  @@suits = ['C', 'D', 'H', 'S']
  @@values = ['2', '3', '4', '5', '6', '7', '8', '9', '10', 'J', 'Q', 
'K', 'A']

  def new(passes = 7)
    @@suits.each do |suit|
      @@values.each do |value|
        @deck.push = Card.new(suit, value)
      end
    end
    shuffle(passes)

    return @deck
  end

  def shuffle(no_of_times)
    max_len = @deck.length
    no_of_times.each do
      for source in (no_of_time..source)
        target = rand(source+1)
        @deck[source], @deck[target] = @deck[target], @deck[source]
      end
    end
  end

  def remove_card
    return @deck.pop
  end

  def print_all
    @deck.each do |card|
      puts card.suit
      puts card.value
    end
  end


require '.\Deck.rb'

@deck = Deck.new()
@deck.print_all()

When I execute this I get the error:
in `print_all': undefined method `each' for nil:NilClass (NoMethodError)

This is exactly the behaviour as described above by OP. I understand why 
now. The variable is not in scope. But how do I create a 'local' 
variable (in my case deck, that can be seen by all methods of the class 
but not be manipulated from outside?
Sorry for this basic question but all courses on Ruby classes that I 
could find online, not one example had a provate class varibale. Surely 
this must be possible?

PS funny that a couple of threads below, it is about card tricks :)

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