Debugging in ruby 1.9

Some things you could try

1) run it with ruby’s normal debugger -rdebug [1] kind of slow

2) run it with unroller gem [kind of stinks, way slow]

3) use a lot of print statements fast, kind of less introspection possible

4) drop to an irb prompt and run some code from there.

you could list the code by creating your own “drop to irb prompt” that listed the code around itself [use caller to discover where you where] then drop to a normal irb prompt.

5) maybe jruby in 1.9 compat mode has a debugger?

[1] http://beaver.net/rdebug/index-0.html

Netbeans is a good IDE for RoR. Good debugger too.

Note: this answer was correct but is now out of date. See the below correct answer. TL;DR: use 'debugger' now.

ruby-debug is now available with Ruby 1.9.x. See http://www.github.com/mark-moseley

To install (using gem on 1.9 Ruby installation):

gem install ruby-debug19

(with perhaps the necessary 'sudo' in front of it).

The ruby 1.9.1-p243 version is out and compitable ruby-debug-ide is also working properly. Install ruby-debug-ide using the following command:

gem install ruby-debug-ide

This will install the ruby-debug-base19 and ruby-debug-ide gems. But before this make sure you install the mingw successfully by following the Development kit docs available from RubyForge.

Latest features are available in ruby-debug-ide19 gem.

UPDATE FOR RUBY 2.0+ and FOLLOWING

byebug is the currently recommended debugger for Ruby 2.0+

This issue has been documented here, and cldwalker, the author of debugger, notes that debugger will be scoped to Ruby 1.9.2 and 1.9.3.

UPDATE 2

It is true that ruby-debug is not actively maintained even if I can't find anywhere that is not maintained any longer.

You can use the new debugger gem if you need a help to start with the new gem you can see Ryan Bates rails cast.

In your Gemfile put:

gem 'debugger', group: [:development, :test]

You can then add a breakpoint anywhere in your code using the debugger keyword.

YOU CAN STILL USE

linecache19 and ruby-debug-base19 with:

bash < <(curl -L https://raw.github.com/gist/1333785)

OLD ANSWERS

Just an add on about this with rvm, ruby 1.9.1-p378. True story is that even if ruby-debug is 1.9.x ready, linecache-0.43 is not. The solution is to install:

gem install ruby-debug19

This solves the problem for me.

OLD UPDATE

If you are having problems with ruby 1.9.2 and Rails 3 debugging putting:

gem 'ruby-debug-base19', "0.11.24"
gem 'ruby-debug19', "0.11.6"

In your Gemfile and doing a

bundle install

Will make you a happy debugger again.

If you still have a problem after installing ruby-debug19 try updating ruby-debug-base19. I had errors and couldn't run WEBrick in debug mode until I did that.

gem update ruby-debug-base19

Oh, and thanks Mr. Moseley for all your hard work!

See my answer here : Ruby-debug not working - Stack Overflow

It's about getting Ruby debugging to work with the following setup

• Mac OS X Lion 10.7.2
• Aptana Studio 3 (Build 3.0.8.201201201658)

• Using rvm, in my project working directory I have a .rvmrc stating:

  rvm use ruby-1.9.3-p0@mygemset
  

I hope this helps!

-- Freddy

ruby-debug19 is not maintained anymore. All the other answers are outdated.

But there's an alternative:

debugger to the rescue!

Put this in your Gemfile:

gem 'debugger', group: [:development, :test]

It just works. - And it is included in the rails Gemfile since 3.2.something to replace ruby-debug19. It has the exact same functionality and is actively maintained.

I used following and it works great for me:

gem 'debugger', group: [:development, :test]

ruby 1.9.3p194 (2012-04-20 revision 35410) [x86_64-linux] rails 3.2.8

doesn't anyone use: ruby -rdebug script.rb

then you can use: b script.rb:## (where ## is the line number of a valid ruby command) otherwise you are going to maybe be in the middle of rubygems or one of your required chunks of code.

Then you can simply set the next breakpoint as b:##

There is a lot of choices, depending on your needs.

I use pry-moves because I can "look back" into what happened inside of previous command by re-executing them in debug mode right from the place.