Support Ruby's builtin debugger

[postmodern]

I noticed that letters require ruby-debug and calls debugger. You can use Ruby's builtin debugger:

require 'debug'
Debug.rb
Emacs support available.

/usr/share/ruby/irb/context.rb:166:
(rdb:1) 

[davejacobs]

I am a big fan of ruby-debug -- what are the tradeoffs between it and the builtin?

[postmodern]

Currently ruby-debug will not compile against MRI 1.9.x, so one has to install the newer debugger gem. Both debugger and the built-in debugger have roughly the same set of commands. The built-in debugger is guaranteed to work on MRI and JRuby; Rubinius has it's own debugger.

Perhaps I should just send you a pull request. :)

[davejacobs]

The ruby-debug I'm requiring there is from the debugger gem (@cldwalker's fork of ruby-debug), so it will compile against YARV. I would like to add JRuby and Rubinius support, so thanks for your PR. What do we lose by not using ruby-debug?

[postmodern]

Nothing apparently? Compare debugger with debug.