Instead of subtracting 10, since the caller method provides filenames, just before the .grep you could call .reject to filter out all the framework code, or perhaps .take_while to stop when you've hit a certain point. (Those would also work for filtering our places you want to turn off tracing.)

Another less hacky but usually slower solution would be the over-powered but under-used set_trace_func, which would give you all the flexibility you need, although I don't know if the trace function is thread-safe (on a phone, rubydoc is a bit hard to search from here).

But, certainly, point taken about it losing its power to illustrate those techniques.