card.rb

module PlayingCards

	class Card
		attr_accessor :rank, :suit
		
		def initialize(a_rank, a_suit)
			@rank = parse_rank a_rank
			@suit = parse_suit a_suit
		end
		
		def > other
			@rank > other.rank
		end

		def < other
			@rank < other.rank
		end
		
		def == other
			@rank == other.rank
		end
		
		private 
		
		def parse_rank a_rank
			case a_rank
			when Fixnum
		 		return a_rank
		 	when String
		 		if (a_rank == "K")
					return 13
			 	elsif (a_rank.to_s == "Q")
			 		return 12
			 	elsif (a_rank.to_s == "J")
			 		return 11
			 	elsif (a_rank.to_i < 11 && a_rank.to_i > 0)
			 		return a_rank.to_i
			 	else
		 			raise InvalidCardError
			 	end
			 end
		end
		
		def parse_suit a_suit
			new_suit = a_suit.to_s.downcase.to_sym
			raise InvalidCardError unless [:hearts, :clubs, :diamonds, :spades].include? new_suit
			return new_suit
		end
		
		class InvalidCardError < Exception
		end
	end
	
	
end

deck.rb

require 'card'

module PlayingCards

	class Deck
		def initialize
			@cards = [1,2,3,4,5,6,7,8,9,10,11,12,13].collect do |r| 
				[:spades, :hearts, :clubs, :diamonds].collect do |s|
					PlayingCards::Card.new(r,s)
				end
			end.flatten
		end
	
		def size
			@cards.size
		end
	
		def deal number_of_cards=1
			return @cards.pop if number_of_cards == 1
		
			result = []
			number_of_cards.times do 
				result << @cards.pop
			end
			result
		end
		
		def peek 
			@cards.last
		end
		
		def shuffle
		end
		
		def sort
		end
	end
end