def on_load(*args, &blk)
      args << :ANY if args.empty?
      proc = blk.to_proc

      # Call proc on registration.
      proc.call()

      # Register callback proc.
      args.each do |name|
        (self.callbacks[name.to_s] ||= []) << proc
      end
    end
def on_load(*args, &blk)
      args << :ANY if args.empty?
      proc = blk.to_proc

      # Call proc on registration.
      proc.call()

      # Register callback proc.
      args.each do |name|
        (self.callbacks[name.to_s] ||= []) << proc
      end
    end
Register a callback when a config has been reloaded. If no config name
 is specified, the callback will be registered under the name :ANY. The
 name :ANY will register a callback for any config file change.

 Example:

   class MyClass
     self.my_config = { }
     RConfig.on_load(:cache) do
       self.my_config = { }
     end
     def my_config
       self.my_config ||= something_expensive_thing_on_config(RConfig.cache.memory_limit)
     end
   end