#! /usr/bin/env ruby

class A
  def foo(arg)
    false
  end

  def self.foo_maker(*args)
    args = args.flatten

    instance_eval "
      def foo(arg)
        #{args.inspect}.include?(arg)
      end
    "
  end
end

class B < A
  foo_maker :a, :b, :c # this fails, undefined method - but if foo_maker is << self, how do I get the instance?
end

a = A.new
b = B.new

puts a.foo(:a) # expected: false
puts b.foo(:a) # expected: true, actual: false
puts b.foo(:d) # expected: false