Being a Ruby noob (and having a background in Groovy), I was a little surprised that you can not access hash objects using the dot notation.  I am writing an application that relies heavily on XML and JSON data.  This data will need to be displayed and I would rather use book.author.first_name over book[‘author’][‘first_name’].  A quick search on google yielded this post on the subject.

So, taking the DRYOO (Don’t Repeat Yourself Or Others) concept.  I came up with this:

   1: class ::Hash

   2:  

   3:   # add keys to hash

   4:   def to_obj

   5:     self.each do |k,v|

   6:       if v.kind_of? Hash

   7:         v.to_obj

   8:       end

   9:       k=k.gsub(/\.|\s|-|\/|\'/, '_').downcase.to_sym

  10:       self.instance_variable_set("@#{k}", v)  ## create and initialize an instance variable for this key/value pair

  11:       self.class.send(:define_method, k, proc{self.instance_variable_get("@#{k}")})  ## create the getter that returns the instance variable

  12:       self.class.send(:define_method, "#{k}=", proc{|v| self.instance_variable_set("@#{k}", v)})  ## create the setter that sets the instance variable

  13:     end

  14:     return self

  15:   end

  16: end

This works pretty well.  It converts each of your keys to properties of the Hash. 

However, it doesn’t sit very well with me because I probably will not use 90% of the properties most of the time.  Why should I go through the performance overhead of creating instance variables for all of the unused ones?

Enter the ‘magic method’ #missing_method:

   1: class ::Hash

   2:   def method_missing(name)

   3:     return self[name] if key? name

   4:     self.each { |k,v| return v if k.to_s.to_sym == name }

   5:     super.method_missing name

   6:   end

   7: end

This is a much cleaner method for my purposes.  Quite simply, it checks to see if there is a key with the given symbol, and if not, loop through the keys and attempt to find one.

I am a Ruby noob, so if there is something I am overlooking, please let me know.