anagram.rb

class Anagram < Struct.new(:base)
  def match(candidates)
    candidates.select do |candidate|
      word.anagram?(candidate)
    end
  end

  def word
    @word ||= AnagramWord.new(base)
  end
end

class AnagramWord < String
  def anagram?(word)
    sorted == AnagramWord.new(word).sorted
  end

  def sorted
    chars.sort
  end
end