Hash keys as accessors in a class

Question

I'm working on a class that reads some sensor information and returns it as a hash. I would like to use the hash keys as accessors, but I'm not having much luck getting it work. Here are the relevant parts of my code so far:

I've tried it both with method_missing and by using the :define_method method.

  attr_reader :sensor_hash

  def method_missing(name, *args, &blk)
    if args.empty? && blk.nil? && @sensor_hash.has_key?(name.to_s)
      @sensor_hash[name.to_s]
    else
      super
    end
  end

  def sensor(*sensor_to_return)
    sensor_output = run_command(this_method_name)
    sensor_output = sensor_output.split("\n")
    sensor_output.map! { |line| line.downcase! }
    unless sensor_to_return.empty?
      sensor_to_return = sensor_to_return.to_s.downcase
      sensor_output = sensor_output.grep(/^#{sensor_to_return}\s/)
    end
    @sensor_hash = Hash.new
    sensor_output.each { |stat| @sensor_hash[stat.split(/\s+\|\s?/)[0].gsub(' ','_').to_sym] = stat.split(/\s?\|\s?/)[1..-1].each { |v| v.strip! } }
    @sensor_hash.each do |k,v|
      puts v.join("\t")
      self.class.send :define_method, k { v.join("\t") }
    end
    return @sensor_hash

The data returned is a hash with the sensor name as the key and and the value is an array of everything else returned. My goal is to be able to call Class.sensor.sensor_name and get the output of Class.sensor[:sensor_name]. Currently, all I'm able to get is an undefined method error. Anybody have any idea what I'm doing wrong here?

Answer 1

Maybe OpenStruct does what you want. From the doc :"It is like a hash with a different way to access the data. In fact, it is implemented with a hash, and you can initialize it with one."

require 'ostruct'
s=OpenStruct.new({:sensor_name=>'sensor1',:data=>['something',1,[1,2,3]]})
p s.sensor_name
#=> "sensor1"

Answer 2

Just a quick example. Do you have any reasons to not monkey-patch your Hash?

irb(main):001:0> class Hash
irb(main):002:1> def method_missing(name, *args, &blk)
irb(main):003:2>   if self.keys.map(&:to_sym).include? name.to_sym
irb(main):004:3>     return self[name.to_sym]
irb(main):005:3>   else
irb(main):006:3*     super
irb(main):007:3>   end
irb(main):008:2> end
irb(main):009:1> end
=> nil
irb(main):012:0> h = {:hello => 'world'}
=> {:hello=>"world"}
irb(main):013:0> h.hello
=> "world"