class ExampleHash < Hash

    def self.regexp(key, icase)
      Regexp.new('\A' + Regexp.quote(key).gsub(/\w+\b/, '\&\w*'), icase)
    end

    def self.candidate(key, icase = false, pat = nil, &block)
      pat ||= ExampleHash.regexp(key, icase)
      candidates = []
      puts "block #{block}"
      block.call do |k, *v|
        puts "INBLOCK"
        (if Regexp === k
           kn = nil
           k === key
         else
           kn = defined?(k.id2name) ? k.id2name : k
           pat === kn
         end) or next
        v << k if v.empty?
        candidates << [k, v, kn]
      end
      candidates
    end

    def candidates(key, icase = false, pat = nil)
      ExampleHash.candidate(key, icase, pat, &method(:each))
    end

    def test
      candidates( "no", false, /(?-mix:\Ano\w*)/ , &method(:each) )
    end

end

puts "`#{ExampleHash[ :no ,"no" ].test}`"