class_method_missing.rb

class A
  def self.foo ; "foo" ; end
  def self.bar ; "bar" ; end
end

class B
  def self.foo ; "another foo" ; end
  def self.method_missing(method_id, *args, &block)
    if A.respond_to?(method_id)
      A.send(method_id, *args, &block)
    else
      super
    end
  end
end

puts B.foo
puts B.bar