Scott Bronson has published a very cool article about the current offerings when it comes to debugging Ruby applications. First off, I appreciate the kind words regarding ruby-debug extension. Second off, he made a very interesting observation:
I hardly ever need a debugger when developing new Ruby on Rails applications.
However, when trying to understand an existing codebase, I find that few things
help more in understanding exactly what is going on than stepping through
the code using a debugger.
I fully subscribe to this idea. I've been developing with Ruby since 2002 and I hardly ever needed a debugger. But there were a couple of times when I really wanted to have a debugger. It was when I ran into a bug in an existing library and I didn't have an intimate knowledge of its internals (no pun intended). It's just much easier to step through the code and see how things are meshed together.
Also, I'd like to make some comments on the current debugger offerings:
There is an official debug.rb library bundled with the standard Ruby distribution. AFAIK, all other debuggers, except maybe Arachno Ruby's one, are based on this small and nifty library, including my ruby-debug. The major drawback of it is the speed of the execution.
Debugger from ZenHack tries to fix this problem by re-implementing trace function in C using RubyInline extension. Unfortunately, it is still quite slow to my taste.
Debugger from Arachno Ruby IDE is very nice, but the last time I checked it used a patched version of Ruby interpreter. Which means that you have to ask for a new patch with each subsequent Ruby release. (But don't quote me on that though :-)
There is another GUI debugger called MrGuid which uses a slightly modified version of debug.rb.
