2016-11-04 15:17:44

attr_accessor_with_history.rb

@@ -0,0 +1,28 @@
+# By alan snape
+# All rights reserved.
+
+class Class
+  def attr_accessor_with_history(attr_name)
+    attr_name = attr_name.to_s # make sure it's a string
+    attr_reader attr_name # create the attribute's getter
+    attr_reader attr_name+"_history" # create bar_history getter
+    class_eval %Q|
+      @#{attr_name} = nil
+      @#{attr_name}_history = nil
+      def #{attr_name}
+        @#{attr_name}
+      end
+      def #{attr_name}=(value)
+        if @#{attr_name} then
+          @#{attr_name}_history.push(@#{attr_name})
+        else
+          @#{attr_name}_history = [@#{attr_name}]
+        end
+        @#{attr_name} = value
+      end
+      def #{attr_name}_history
+        @#{attr_name}_history
+      end
+    |
+  end
+end

dessert.rb

@@ -0,0 +1,30 @@
+# By alan snape
+# All rights reserved.
+
+class Dessert
+  attr_accessor :name, :calories
+  def initialize(name, calories)
+    self.name = name
+    self.calories = calories
+  end
+  def healthy?
+    return self.calories < 200
+  end
+  def delicious?
+    return true
+  end
+end
+
+class JellyBean < Dessert
+  attr_accessor :flavor
+  def initialize(flavor)
+    self.flavor = flavor
+    self.calories = 5
+  end
+  def name
+    return self.flavor + ' jelly bean'
+  end
+  def delicious?
+    return 'licorice' != self.flavor
+  end
+end

fun_with_strings.rb

@@ -0,0 +1,31 @@
+# By alan snape
+# All rights reserved.
+
+module FunWithStrings
+  def palindrome?
+    str = self.downcase.gsub(/(\W|\d)/, '')
+    return str == str.reverse
+  end
+  def count_words
+    w = {}
+    self.downcase.split(/\W+/).each do |i|
+      w.has_key?(i) ? w[i] += 1 : w[i] = 1
+    end
+    w.delete("")
+    return w
+  end
+  def anagram_groups
+    w = {}
+    self.split.each do |s| 
+      i = s.downcase.chars.sort.join
+      w.has_key?(i) ? w[i].push(s) : w[i] = [s]
+    end
+    return w.values
+  end
+end
+
+# make all the above functions available as instance methods on Strings:
+
+class String
+  include FunWithStrings
+end

rock_paper_scissors.rb

@@ -0,0 +1,49 @@
+# By alan snape
+# All rights reserved.
+
+class RockPaperScissors
+
+  # Exceptions this class can raise:
+  class NoSuchStrategyError < StandardError; end
+
+  # check strategy is legal or not
+  def self.checkStrategy(stg)
+    if 'P' != stg && 'R' != stg && 'S' != stg then
+      raise NoSuchStrategyError, 'Strategy must be one of R,P,S'
+    end
+  end
+
+  # a single round game
+  def self.winner(player1, player2)
+    stg1, stg2 = player1[1], player2[1]
+    self.checkStrategy(stg1)
+    self.checkStrategy(stg2)
+    if stg1 == stg2 then
+      return player1
+    elsif 'P' == stg1 && 'S' == stg2 then
+      return player2
+    elsif 'S' == stg1 && 'P' == stg2 then
+      return player1
+    else
+      return stg1 < stg2 ? player1 : player2
+    end
+  end
+
+  # if there is a sub game then returns the winner of it
+  # else return this player himself
+  def self.tournament_match(game)
+    if game[0].kind_of?(Array) then
+      return self.tournament_winner(game)
+    else
+      return game
+    end
+  end
+
+  # tournament game rounds
+  def self.tournament_winner(tournament)
+    player1 = self.tournament_match(tournament[0])
+    player2 = self.tournament_match(tournament[1])
+    return self.winner(player1, player2)
+  end
+
+end