2014-03-11 Null Object Part 2

nil_duck_final.rb

class NilDuck < NilObject
  def name
    'Demo Duck'
  end

  def status
    'sleeping'
  end

  def color
    'gray'
  end

  def migratory?
    true
  end
end

nil_duck_intermediate.rb

class NilDuck < NilObject
  def initialize
    super(Duck)
  end

  def name
    'Demo Duck'
  end
 
  def status
    'sleeping'
  end
 
  def color
    'gray'
  end
 
  def migratory?
    true
  end
end

nil_duck_previous.rb

class NilDuck
  def name
    'Demo Duck'
  end

  def status
    'sleeping'
  end

  def color
    'gray'
  end

  def migratory?
    true
  end

  def method_missing(name, *args)
    super unless Duck.new.respond_to?(name)
    name.ends_with?('?') ? false : nil
  end
end

nil_goose_final.rb

class NilGoose < NilObject
  def name
    'Demo Goose'
  end
 
  def status
    'awake'
  end
 
  def color
    'black'
  end
 
  def migratory?
    true
  end
end

nil_goose_initial.rb

class NilGoose
  def name
    'Demo Goose'
  end
 
  def status
    'awake'
  end
 
  def color
    'black'
  end
 
  def migratory?
    true
  end
 
  def method_missing(name, *args)
    super unless Goose.new.respond_to?(name)
    name.ends_with?('?') ? false : nil  end
end

nil_goose_intermediate.rb

class NilGoose < NilObject
  def initialize
    super(Goose)
  end

  def name
    'Demo Goose'
  end
 
  def status
    'awake'
  end
 
  def color
    'black'
  end
 
  def migratory?
    true
  end
end

nil_object_1.rb

class NilObject
  def initialize(klass)
    @klass = klass
  end

  def method_missing(name, *args)
    return super unless @klass.new.respond_to?(name)
    name.to_s.ends_with?('?') ? false : nil
  end
end

nil_object_2.rb

class NilObject
  def initialize(klass=nil)
    @klass = klass || real_class_name
  end

  def method_missing(name, *args)
    return super unless @klass.new.respond_to?(name)
    name.to_s.ends_with?('?') ? false : nil
  end

  def real_class_name
    self.class.name[3..-1].constantize
  end
end

nil_object_final.rb

class NilObject
  def initialize(klass=nil)
    @klass = klass || real_class_name
  end

  def method_missing(name, *args)
    return super unless respond_to?(name)
    name.to_s.ends_with?('?') ? false : nil
  end

  def respond_to?(name)
    @klass.new.respond_to?(name)
  end

  def real_class_name
    self.class.name[3..-1].constantize
  end
end