Audit time taken by different methods

audit.rb

def audit(klass, method)
  klass.class_eval do
    define_method :"#{method}_with_audit" do |*args|
      result = nil
      time = Benchmark.realtime do
        result = send(:"#{method}_without_audit", *args)
      end
      $time ||= {}
      $time[klass] ||= {}
      $time[klass][method] ||= 0
      $time[klass][method] += time
      result
    end
    alias_method_chain method, :audit
  end
end

audit FooClass, :some_method