Preface
Overcomplicated specifications lead to overcomplicated implementations. Lately I've been fixing issues with ActionWebService framework - a soon to be removed part of Ruby on Rails. I have to use SOAP in the web application I'm developing. My client needs to keep his product inventory in a good shape and he requested to implement some of the inventory management functionality using handheld devices. There is a .Net environment available for this kind of devices and it works very well. So I desperately needed a functional web service implementation for Rails. That why I volunteered to fix AWS. And that's when I found out that ruby-breakpoint just doesn't cut it. Don't get me wrong, soap4r is a fine piece of software, but SOAP is difficult and obscure, which leads to complicated libraries that implement it. The situation is even worse when such libraries have almost no documentation whatsoever.
So instead of just stopping at some point in your program to examine the environment (the facility offered by ruby-breakpoint library), ruby-debug extension offers the full-fledged debugger for Ruby. The main difference between ruby-debug and the standard debug.rb library is the speed of the execution. Major problem with debug.rb is that it uses Kernel#set_trace_func method, which requires creation of Binding object for each hook invocation. It is fine for small scripts, but for the real world applications like Rails ones, debug.rb is almost impossible to use. You just sit and watch how Ruby interpreter creates enormous amount of Binding objects, just in order to destroy them with the immediate garbage collection cycle. It also explains that ruby-debug doesn't support watchpoints for the same reason.
