for responding with JSON

result.rb

module Result
  ::R = ::Result

  def self.create(result = nil, error = nil, code = 0)
    Data.new(result, error, code)
  end

  def self.create_error(error = nil, code = 1)
    Data.new(nil, error, code)
  end

  class Data
    attr_accessor :result, :error, :code

    def initialize(result = nil, error = nil, code = 0)
      @result = result
      @error = error
      @code = code
    end

    def error(message = nil, code = 1, reset = false)
      if message.nil?
        @error
      else
        @result = nil if reset
        @error = message
        @code = code
      end
    end

    def <<(value)
      if value.is_a?(Hash)
        @result = {} unless @result.is_a?(Hash)
        @result.merge! value
      else
        @result = value
      end

      self
    end

    def []=(key, value)
      @result = {} if @result.nil?
      @result[key] = value;
    end

    def [](key)
      @result = {} if @result.nil?
      @result[key]
    end

    def set(key, value)
      instance_variable_set to_instance_variable_symbol(key), value
    end

    def get(key)
      key = to_instance_variable_symbol key
      instance_variable_defined?(key) ? instance_variable_get(key) : nil
    end

    def to_hash
      Hash[instance_variables.map {|variable|
        [variable.to_s[1..-1].to_sym, instance_variable_get(variable)]
      }]
    end

    protected

    def to_instance_variable_symbol(value)
      value = value.to_s if value.is_a?(Symbol)
      '@'.concat(value).to_sym
    end
  end

  class HTTPError < StandardError
    attr_accessor :data, :status

    def initialize(status = 500, message = nil, data = nil)
      super message

      @status = status

      if data.nil?
        @data = R.create_error(message)
      elsif data.is_a?(Data)
        @data = data
        @data.error = message if not message.nil? and @data.error.nil?
      else
        @data = R.create(data, message, 1)
      end
    end
  end
end