Merge pull request #11 from Sirupsen/os-specific-gems

OS-specific gems

README.md

@@ -389,10 +389,34 @@ the same purpose of the named scope and returns and
 ## Bundler
 
 * Put gems used only for development or testing in the appropriate group in the Gemfile.
-* Avoid OS specific gems. Bundler has no facilities to deal with those properly.
 * Use only established gems in your projects. If you're contemplating
 on including some little-known gem you should do a careful review of
-its source code first.
+its source code first. 
+* OS-specific gems will by default result in a constantly changing `Gemfile.lock` 
+for projects with multiple developers using different operating systems.
+Add all OS X specific gems to a `darwin` group in the Gemfile, and all Linux 
+specific gems to a `linux` group:
+
+    ```Ruby
+    # Gemfile
+    group :darwin do
+      gem 'rb-fsevent'
+      gem 'growl'
+    end
+
+    group :linux do
+      gem 'rb-inotify'
+    end
+    ```
+
+To require the appropriate gems in the right environment, add the
+following to `config/application.rb`:
+
+    ```Ruby
+    platform = RUBY_PLATFORM.match(/(linux|darwin)/)[0].to_sym
+    Bundler.require(platform)
+    ```
+
 * Do not remove the `Gemfile.lock` from version control. This is not
   some randomly generated file - it makes sure that all of your team
   members get the same gem versions when they do a `bundle install`.