Subclassing a Ruby core class

gistfile1.rb

class Storage
  attr_reader :elements

  def initialize
    @elements = {}.tap do |elements|
      elements[:people] = []
      elements[:places] = []
    end
  end

  def size
    @elements.size
  end

  def get(key)
    @elements.fetch(key)
  end
end

storage = Storage.new

puts storage.inspect
puts storage.size
puts storage.get(:people).inspect

class HashStorage < Hash
  def initialize
    self[:people] = []
    self[:places] = []
  end

  alias :get :fetch
end

storage = HashStorage.new

puts storage.inspect
puts storage.size
puts storage.get(:people).inspect