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Reflexive is a web based live class and source code browser
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Reflexive is a web based live class and source code browser. It's meant to simplify navigating the code bases which make heavy use of metaprogramming techniques and/or have large amount of classes dispersed between many files. Particularly I wrote it to have a better tool to navigate Arel source code.

Live means that it runs next to your loaded application and reflects on the actual live classes. Since most of the metaprogramming tricks happen at load time we can get precise information on what the classes are composed of, which methods they respond etc. That's something that is either impossible or very hard with the static code analysis tools like RDoc or YARD.

Reflexive is a Sinatra app and can be used stand-alone or mounted as Rack app from your Rails application. Reflexive is based on standard 1.9.2 Ruby library utilizing Method/UnboundMethod classes, methods/instance_methods methods for reflection and Ripper parser for code navigation. Checkout Reflexive: Live Class And Source Code Browser blog post for longer introduction.


Class Browser

Check out sample output for Date, FileUtils, ActiveRecord::Base classes.

Note: demo project is running on Heroku with Ruby 1.9.1 which has some known issues with reflection capabilities which are fixed in 1.9.2, consult Ruby 1.9.1 Known Bugs section for details.

It includes

  1. Class ancestor chain

  2. Files in which methods of the class were defined

  3. Constants nested inside module/class

  4. Class descendants

  5. Class and instance methods grouped by class/module they're defined in and visibility. Clicking on any method leads to the method definition opened in Source Browser.

Source Browser

Check out sample output for uri/common.rb, ostruct.rb, rubygems.rb files.

Features include: clicking constants will try to open them in Class Browser, method calls with constant receiver or without explicit receiver will be resolved according to Method Lookup section and open the target method in Source Browser. Clicking blabla in require "blabla" will take you to the blabla.rb, and clicking local variable will highlight the place where the variable was introduced with acid pink (ouch!) background.

Method Call Lookup

Methods called without explicit receiver are searched according to the following algorithm

  1. Look for the method defined by the class

  2. Look for methods defined by derived classes or including modules, i.e. by going down the inheritance tree

  3. When all of the above fails last resort lookup which just searches the named method in all classes.


Reflexive requires the most recent version of Ruby you can get. With RVM installed

> rvm install ruby-1.9.2-head
> rvm use ruby-1.9.2-head
> gem install reflexive


Rails 3.0.0.beta3 and higher

Add to your application Gemfile

gem "reflexive"

Add to config/application.rb

config.middleware.insert_after("Rack::Lock", "Reflexive::Application")

Run the server in production environment with

rails server --environment=production

Reflexive Dashboard should be available at http://localhost:3000/reflexive/dashboard

Rails 2.3.x

Add to your application config/environment.rb file

config.gem "reflexive"
config.middleware.insert_after("Rack::Lock", "Reflexive::Application")

Run the server in production environment with

ruby script/server --environment=production

Reflexive Dashboard should be available at http://localhost:3000/reflexive/dashboard


If you want to use Reflexive outside of Rack environment just place the following lines in your script

require "reflexive/application"!

This will block execution and start Reflexive as stand-alone Sinatra app. Reflexive Dashboard should be available at http://localhost:4567/reflexive/dashboard

Ruby 1.9.1 Known Bugs

  1. Class methods are reported as owned by class even when they are only inherited (leads to a lot of class methods reported incorrectly)

  2. Can't locate methods created with attr_reader/writer


> git clone git://
> cd reflexive
> bundle install # install gems required in development
> rbdev # place ./lib on $RUBYLIB, see
> rake # run specs
> SINATRA_RELOADER=1 bundle exec rackup -p 4567 -s thin # run development server with class reloading

MIT License. Copyright © 2010 Evgeniy Dolzhenko.

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