WatchPoint

Stop exactly where a variable gets changed (a.k.a. watchpoints or trace_var for all) and help you swim through (other people's) code faster.

According to this page on ruby-doc.org there used to be watchpoints built into RDebug but I can't seem to find it in 1.9.3 and 2.0.0 on Mac. It turned out to be quite easy to roll your own so here goes.

Example

require 'watch_point'

def hello(girl)
  girl << " Baby"
  puts "Hello, #{girl}"
end

name = "Mary"

# Watch any variables!
WatchPoint.watch(name)

WatchPoint.enable

hello(name)

WatchPoint.disable

You'll get a Pry prompt at the hello line:

From: foo.rb @ line 4 Object#hello:

    3: def hello(girl)
 => 4:   girl << " Baby"
    5:   puts "Hello, #{girl}"
    6: end

[1] pry(main)>

Installation

Add this line to your application's Gemfile:

gem 'watch_point'

And then execute:

$ bundle

Or install it yourself as:

$ gem install watch_point

Contributing

  1. Fork it
  2. Create your feature branch (git checkout -b my-new-feature)
  3. Commit your changes (git commit -am 'Add some feature')
  4. Push to the branch (git push origin my-new-feature)
  5. Create new Pull Request