module_parent_name

# File activesupport/lib/active_support/core_ext/module/introspection.rb, line 10
  def module_parent_name
    if defined?(@parent_name)
      @parent_name
    else
      parent_name = name =~ /::[^:]+\z/ ? -$` : nil
      @parent_name = parent_name unless frozen?
      parent_name
    end
  end