Base = Struct.new :foo, :bar do
  def hash
    members.inject(0) {|h,m| ((h << 2) ^ self[m].hash) & 0xFFFF}
  end

  def ==(o)
    members.all? {|m| self[m] == o[m]}
  end
end

class X < Base
end
class Y < Base
end
x = X.new 1,2
y = Y.new 1,2
p x == y