dryer_code.rb

class Dryer = Struct.new(:file_path, :super_class, :blk) do
  def self.def_class(file_path, super_class=Object, &blk)
    new(file_path, super_class, blk).def_class
  end

  def def_class
    constant_names.each.with_index.inject(Object) do |const, (next_const, index)|

      if constant_names.length == index + 1

        # this is needed to set the class name so that activerecord
        # works properly.
        klass = const.const_set(next_const, Class.new(super_class))

        # here we eval the class block to define methods and everything
        klass.class_eval &blk
      else
        const.const_get(next_const)
      end
    end
  end

  def constant_names
    get_namespaces.split('/').map(&:camelcase)
  end

  def get_namespaces
    # this assumes you are following ruby convention of paths corresponding to
    # namespaces. If you do not, this can't work.
    file_path.gsub(most_likely_relative_path, '').gsub(".rb", '')
  end

  def most_likely_relative_path
    # sort by length selects the path closest to the original file path.
    possible_relative_paths.sort_by(&:length).last + '/'
  end

  def possible_relative_paths
    $LOAD_PATH.select{|p| file_path[/^#{p}/]}
  end
end