Sample of some class method and class-instance-var inheritance

dataholder.rb

class DataHolder
  class << self
    attr_accessor :data1, :data2
    def use_data
      puts "I have #{data1} and #{data2}"
    end
  end
end

class DataHolderAlpha < DataHolder
end

class DataHolderBeta < DataHolder
end

DataHolder.data1 = "plain"
DataHolder.data2 = "jane"
DataHolder.use_data

# do something awesome here
DataHolderAlpha.data1 = "Alpha"
DataHolderAlpha.data2 = "Foo"

DataHolderBeta.data1 = "Beta"
DataHolderBeta.data2 = "Bar"

DataHolderAlpha.use_data
DataHolderBeta.use_data

# make sure these classes aren't bumping into each other
[DataHolder, DataHolderAlpha, DataHolderBeta].each do |klass|
  klass.use_data
end