attr_sec_accessor module add-on advanced

class Module
  def attr_sec_accessor(sym, *args, &block)
    if block.nil? # default actions
      args = [0] if args.size == 0 #default = 0
      if args.size < 2 # One pair
        attr_writer sym
        attr_sec_reader sym, *args
      else # loads of methods followed by a default value.
        default = args[-1]
        syms = [sym].concat(args)
        syms.pop
        for sym in syms
          attr_writer sym
          attr_sec_reader sym, default
        end
      end
    else # when a block is given
      # currently just pair sematics
      args.unshift(sym)
      i = 0
      while i < args.size
        attr_writer args[i]
        attr_sec_reader args[i], args[i+1]
        i += 2
      end
    end
  end

  def attr_sec_reader(sym, default = 0)
    sym = sym.id2name
    string = "def #{sym};" +
             "  @#{sym} = #{default}  if @#{sym}.nil?;" +
             "  @#{sym};" +
             "end;"
    module_eval(string)
  end
end