gistfile1.rb

class A
  def self.name; 'A'; end
  def self.f; "#{name}#{superclass.f if superclass.respond_to? :f}"; end
end

class B < A
  def self.name; 'B'; end
end

class C < B
  def self.name; 'C'; end
end

class D < C
  def self.name; 'D'; end
end

# call
# D.f
# 'DCBA'