dispatcher.rb

class Object
  def send_through(object, *args)
    object.dispatcher_for(self).call(self, *args)
  end
end

module Dispatcher
  class DispatcherNotFound < StandardError; end

  def self.extended(klass)
    klass.class_eval { @dispatchers = {} }
  end

  def for(kind, &block)
    @dispatchers[kind] = block
  end

  def dispatcher_for(object)
    return @dispatchers[object.class] ||= begin
      klass = object.class
      until klass == Object
        if @dispatchers.key?(klass)
          return @dispatchers[object.class] = @dispatchers[klass]
        end
        klass = klass.superclass
      end

      raise DispatcherNotFound, "No #{self} dispatcher for #{object.class}"
    end
  end
end

example.rb

module Camelize
  extend Dispatcher
end

Camelize.for(String) do |string|
  string.gsub(/\/(.?)/) { "::#{$1.upcase}" }.gsub(/(?:^|_)(.)/) { $1.upcase }
end

Camelize.for(Object) do |object|
  ""
end

p "hello_hello".send_through(Camelize)
p nil.send_through(Camelize)