Dynamically instantiate classes by method call, recursive until method call is a class to work with Modules

class_initer.rb

# Dynamically instantiate classes by method call, recursive until method call is a class to work with Modules
# Given classes Foo and Bar::Foo exist
#
# app.foo => Foo.new
# app.bar.foo => Bar::Foo.new
#
# Note: requires classes to be pre-required/loaded - ie will not work with Rails
# lazy class loading
#
class App
  def initialize(base_mod = Kernel)
    @base_mod = base_mod
  end

  def method_missing(method_name, *args, &block)
    if valid_method_name?(method_name)
      create_klass_or_new(method_name)
    else
      super
    end
  end

  def respond_to_missing?(method_name, *)
    valid_method_name?(method_name) || super
  end

  private

  def valid_method_name?(method_name)
    @base_mod.const_defined? method_name_to_class_or_module(method_name)
  end

  def create_klass_or_new(method_name)
    klass_const = @base_mod.const_get method_name_to_class_or_module(method_name)
    if klass_const.instance_of? Module
      self.class.new(klass_const)
    else
      klass_const.new
    end
  end

  def method_name_to_class_or_module(method_name)
    method_name.to_s.camelize
  end
end

memoized_class_initer.rb

# Dynamically instantiate classes by method call, recursive until method call is a class to work with Modules.
# Memoize the method call result.
# Given classes Foo and Bar::Foo exist
# app.foo => Foo.new
# app.bar.foo => Bar::Foo.new
#
# Note: requires classes to be pre-required/loaded - ie will not work with Rails
# lazy class loading
#
class App
  def initialize(base_mod = Kernel)
    @base_mod = base_mod
  end

  def method_missing(method_name, *args, &block)
    if valid_method_name?(method_name)
      define_accessor_for_class_or_module(method_name)
      public_send(method_name)
    else
      super
    end
  end

  def respond_to_missing?(method_name, *)
    valid_method_name?(method_name) || super
  end

  private

  def valid_method_name?(method_name)
    @base_mod.const_defined? method_name_to_class_or_module(method_name)
  end

  def define_accessor_for_class_or_module(method_name)
    klass_const = @base_mod.const_get method_name_to_class_or_module(method_name)
    if klass_const.instance_of? Module
      define_memoized_getter(method_name, self.class.new(klass_const))
    else
      define_memoized_getter(method_name, klass_const.new)
    end
  end

  def define_memoized_getter(method_name, value_to_assign)
    self.class.send(:define_method, method_name) do
      unless instance_variable_defined?("@_#{method_name}")
        instance_variable_set("@_#{method_name}", value_to_assign)
      end
      instance_variable_get("@_#{method_name}")
    end
  end

  def method_name_to_class_or_module(method_name)
    method_name.to_s.camelize
  end
end