From: John Turner <xennocide@...>
Date: 2006-09-29T21:25:15+09:00
Subject: Re: Accessing Nested Hashes Directly

atraver@gmail.com wrote:
> This method can be called like this:
> 
>   first_name = get_value(params, :body, :user, :name, :given)
> 
> It will traverse the hash and kick back a nil at the first problem it
> finds instead of raising an exception, or will return the value if it
> actually exists.
> 
> Here's my question, though: is this code efficient? Is there a better
> way? Am I missing something fundamental in Ruby that would solve this
> without the need for the new method?
> 

I didn't really like the way that method is called, doesn't seem very 
"ruby" exactly.  Came up with the following which is really dirty at the 
moment but I prefer how it's called.  The method_missing in NilClass is 
kind of unforgivably dirty.  Would like to see improvements I guess, but 
not sure there's really a way to do this nicely:

So, yeah, don't use this, but possibly be amused by it anyway:

require 'ostruct'
class NestStruct < OpenStruct
   def self.fromNestedHash(h)
     struct = NestStruct.new(h)
     struct.marshal_dump.keys.each do |key|
       if struct.send(key).is_a? Hash
         struct.send(key.to_s + '=', fromNestedHash(struct.send(key)))
       end
     end
     return struct
   end

   def method_missing(m, *args)
     super(m, args)
   rescue NoMethodError
     nil
   end
end

class NilClass
   def method_missing(m, *args)
     nil
   end
end

h = {
   'name' => {
     'first' => 'Ross'
   },
   'contact' => {
          'phone' => {
       'office' => '345345'
     }
   }
}

s = NestStruct.fromNestedHash(h)
puts s.contact.phone # => #<NestStruct office="345345">
puts s.contact.phone.office # => 345345
puts s.contact.phone.home # => nil
puts s.foo.bar # => nil