gistfile1.rb

class HashMemoize
  def memoized_value key
    @memo_hash ||= Hash.new { |hsh, new_key| hsh[new_key] = some_heavy_computation new_key }
    @memo_hash[key]
  end
  
  private
  def some_heavy_computation key
    puts "heavy duty for #{key} !"
    key * 2
  end
end