gistfile1.rb

module Facter
  def self.add(name, &block)
    collection.add(name, &block) # eventually becomes Factor::Util::Resolvers.instance_eval(block)
  end
end

class Factor::Util::Resolvers
  class << self
    def setcode(string=nil, &block)
      return Facter::Util::Resolvers::Exec.new(string) if string
      return Facter::Util::Resolvers::Proc.new(block) if block
      raise ArgumentError, "You must pass either code or a block"
    end
  end
end