Wraps rb_add_event_hook so you can write fast ruby event hook processors w/o the speed penalty that comes with set_trace_func (sooo sloooow!). Calls back into ruby so you don't have to write C. % ruby demo.rb # of iterations = 1000000 user system total real null_time 0.120000 0.000000 0.120000 ( 0.125279) ruby time 0.560000 0.000000 0.560000 ( 0.562834) event hook 3.160000 0.010000 3.170000 ( 3.175361) set_trace_func 34.530000 0.100000 34.630000 ( 34.942785)