SaaS-Class: Homework 2

cartesian.rb

class CartesianProduct
  include Enumerable
  
  def initialize(a,b)
    @values = []
    @values = a.product(b) unless b.empty?
  end
  
  def each(&block)
    @values.each {|v| yield v}
  end
  
end

c = CartesianProduct.new([:a,:b], [4,5])
c.each { |elt| puts elt.inspect }

c = CartesianProduct.new([:a,:b], [])
c.each { |elt| puts elt.inspect }

currency.rb

class Numeric
  
  @@currencies = {'yen' => 0.013, 'euro' => 1.292, 'rupee' => 0.019, 'dollar' => 1.0}
  
  def method_missing(method, *args)
    
    singular_currency = (method == :in ? args.first : method).to_s.gsub(/s$/, '')
    
    if @@currencies.has_key?(singular_currency)
      self.send(method == :in ? :/ : :*, @@currencies[singular_currency])
    else
      super
    end
    
  end
  
end

class String
  
  def palindrome?
    
    self.gsub!(/\W+/, '').downcase!
    
    self == self.reverse
    
  end
  
end

module Enumerable
  
  def palindrome?
    self.to_a == self.to_a.reverse
  end
  
end

p 5.dollar.in(:rupees)
p 5.rupees.in(:yen)
p 5.rupees.in(:yen).between?(7.2, 7.4)

p "A man, a plan, a canal -- Panama".palindrome?
p [1,2,3,2,1].palindrome?