Ruby hash - how to use hash value when populating object?

Question

For a pack of playing cards:

How can I use the suit hash (below) when creating a pack?

I have:

class PackOfCards

  SUITS={H: 'Hearts', S:'Spades', D:'Diamonds', C:'Clubs'}
  CARDS=['A','2','3','4','5','6','7','8','9','10','J','Q','K']


  attr_accessor :pack_name, :cards

  def initialize(pack_name)

    @pack_name= pack_name
    @cards = []
    (0..3).each do |suit|
      (0..12).each do |number|
        @cards << PlayingCard.new(self, (SUITS[suit].value), CARDS[number])
      end 
    end 
  end 
end

class PlayingCard

  attr_accessor :pack, :card_number, :card_suit


  def initialize(pack, suit, number)
    @card_suit = suit
    @card_number = number
  end 

end

but I get:

pack_of_cards.rb:16:in `block (2 levels) in initialize': 
undefined method `value' for 
{:H=>"Hearts", :S=>"Spades", :D=>"Diamonds", :C=>"Clubs"}:Hash (NoMethodError)

Updated to use hash's {} syntax (not []) but same error :( — junky
– junky, Commented Mar 17, 2013 at 17:01

sawa · Accepted Answer · 2013-03-17 17:01:30Z

2

~~Your SUITS is invalid expression.~~ Perhaps you wanted to do this:

SUITS = %w[Hearts Spades Diamonds Clubs]

And it is not clear what you are doing, but perhaps you should be doing this:

@cards =
SUITS.flat_map{|suit| CARDS.map{|number| PlayingCard.new(self, suit, number)}}

answered Mar 17, 2013 at 17:01

sawa

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Comments

Intrepidd · Accepted Answer · 2013-03-17 17:04:32Z

1

Here is a corrected version, check the comments :

class PackOfCards
  SUITS={H: 'Hearts', S:'Spades', D:'Diamonds', C:'Clubs'} # Use curly braces to define a hash, [] braces will define an array containing one hash
  CARDS=['A','2','3','4','5','6','7','8','9','10','J','Q','K']
  attr_accessor :pack_name, :cards

  def initialize(pack_name)
    @pack_name= pack_name
    @cards = []
    SUITS.each_key do |suit| # each_key is better since it gives you the key of the hash
      (0..12).each do |number|
        puts PackOfCards::SUITS[suit]
        @cards << PlayingCard.new(self, (PackOfCards::SUITS[suit]), PackOfCards::CARDS[number]) # Call the hash with the right key to get the Suit
      end
    end
  end
end

class PlayingCard 
  attr_accessor :pack, :card_number, :card_suit

  def initialize(pack, suit, number)
    @card_suit = suit
    @card_number = number
  end

end

answered Mar 17, 2013 at 17:04

Intrepidd

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2 Comments

junky Over a year ago

Yes, I like it. I changed the PackOfCards::SUITS[suit] expression to SUITS[suit] as it is within the class. I welcome thoughts on that change :)

junky Over a year ago

btw (others) I am using a hash rather than an array (which I used initially) because ultimately I want be to able to use either the one letter suit name or the full description. Right now I could also just use an array and grab the capitalized first letter, but this is homework (that I set myself) and wanted to see how to use a hash in this context.

Srikanth Venugopalan · Accepted Answer · 2013-03-17 17:01:41Z

0

Your Suit definition and lookup don't look valid.

How about something like this (assuming the output is a pack of cards with all suit and numbers) -

class PackOfCards

  SUITS = ['Hearts', 'Spades', 'Diamonds', 'Clubs']
  CARDS=['A','2','3','4','5','6','7','8','9','10','J','Q','K']


  attr_accessor :pack_name, :cards

  def initialize(pack_name)

    @pack_name= pack_name
    @cards = []
    (0..3).each do |suit|
      (0..12).each do |number|
        @cards << PlayingCard.new(self, (SUITS[suit]), CARDS[number])
      end 
    end 
  end 
end

class PlayingCard

  attr_accessor :pack, :card_number, :card_suit


  def initialize(pack, suit, number)
    @card_suit = suit
    @card_number = number
  end 

end

answered Mar 17, 2013 at 17:01

Srikanth Venugopalan

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Comments

AdamT · Accepted Answer · 2013-03-17 17:03:15Z

0

You've actually put a hash in an array. To access the key, value pairs you'd have to access the array element first like this:

SUITS.first[:H]

answered Mar 17, 2013 at 17:03

AdamT

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