Refactoring examples using code taken from SpamBitch.

spam_bitch_refactoring.rb

# Original
class Spammer 
  def initialize
    @random_telephones = Proc.new { "787-#{rand(000..999)}-#{rand(0000..9999)}" }
    @sms_telephones = Proc.new { "787#{rand(000..999)}#{rand(0000..9999)}" }
  end
  
  def telephone
    @random_telephones.call
  end
  
  def sms(carrier)
    case carrier
    when 'claro'
      "#{@sms_telephones.call}@vtexto.com"
    when 'att'
      "#{@sms_telephones.call}@txt.att.net"
    when 'tmobile'
      "#{@sms_telephones.call}@sms.tmobile.net"
    else
      raise "Carrier not Supported"
    end
  end  
end 

# Refactor 1
module SpamBitch  
  module Phone
    def self.telephone
      "787-#{rand(000..999)}-#{rand(0000..9999)}"
    end
  
    def self.sms(carrier='')
      gateway = case carrier
        when 'claro'
          'vtexto.com'
        when 'att'
          'txt.att.net'
        when 'tmobile'
          'sms.tmobile.net'
        else
          raise "Carrier not Supported"
        end
      "#{telephone.gsub(/-/, '')}@#{gateway}"
    end 
  end
end

# Refactor #2
module SpamBitch  
  module Phone
    def self.carriers
      { claro: 'vtexto.com', att: 'txt.att.net', tmobile: 'sms.tmobile.net' }
    end
    
    def self.telephone
      "787-#{rand(000..999)}-#{rand(0000..9999)}"
    end
    
    def self.sms(carrier='')
      gateway = carrier.empty? ? carriers[carriers.keys[rand(carriers.length)]] : carriers[carrier] 
      "#{telephone.gsub(/-/, '')}@#{gateway}"
    end  
  end
end 

# Refactor #3 (Final version... so far.)
module SpamBitch  
  module Phone
    def self.carriers
      { claro: 'vtexto.com', att: 'txt.att.net', tmobile: 'sms.tmobile.net' }
    end
    
    def self.random_carrier
      carriers.keys[rand(carriers.length)]
    end
    
    def self.telephone
      "787-#{rand(000..999)}-#{rand(0000..9999)}"
    end
    
    def self.sms(carrier='')
      gateway = carrier.empty? ? carriers[random_carrier] : carriers[carrier] 
      "#{telephone.gsub(/-/, '')}@#{gateway}"
    end  
  end
end