NestedHash Class

Question

I want to make a Ruby nested hash table class to avoid repeating ugly code and to keep my programs as true to the OOP paradigm as I can. Are there any ways to make this class definition smaller and/or simpler?

To clarify, the class essentially creates an arbitrarily-deep hash table. For example, if you had a NestedHash object called foo, you could write foo[:a][:b][:c] = 1.

class NestedHash
 include Enumerable
 def initialize
 @outer = Hash.new { |hash, key| hash[key] = Hash.new(&hash.default_proc) }
 end
 def keys
 @outer.keys
 end
 def values
 @outer.values
 end
 def [](key)
 @outer[key]
 end
 def []=(key, value)
 @outer[key] = value
 end
 def each
 @outer.each { |key, value| yield(key, value) }
 end
end

Answer 1

So really, the meat of your whole program is in the single line of the constructor. The rest of it is just forwarding methods to @outer. So we should do that explicitly:

require 'forwardable'
class NestedHash
 extend Forwardable
 include Enumerable
 def_delegators :@outer, :[], :[]=, :keys, :values, :each
 def initialize
 @outer = Hash.new { |hash, key| hash[key] = Hash.new(&hash.default_proc) }
 end
end
h = NestedHash.new
h[:a][:b] = 99
p h[:a][:b] #=> 99

Keep in mind that you can get the same effect also by just doing:

module NestedHash
 def self.create
 Hash.new { |hash, key| hash[key] = Hash.new(&hash.default_proc) }
 end
end

and use it like:

h = NestedHash.create