The TextMate bundle that first appeared in the famous "Rails 15 minute video." This is it, many years later.

To install via Git:

mkdir -p ~/Library/Application\ Support/TextMate/Bundles
cd ~/Library/Application\ Support/TextMate/Bundles
git clone git://github.com/drnic/ruby-tmbundle.git "Ruby.tmbundle"
osascript -e 'tell app "TextMate" to reload bundles'

Source can be viewed or forked via GitHub: http://github.com/drnic/ruby-tmbundle

When you save a Ruby file, it will first validate the syntax and print any validation error as a tooltip.

You can get more detailed syntax error information if you have Rubinius installed (and rbx in TextMate's $PATH).

If you have Homebrew installed:

brew install rubinius

Then in TextMate, add your homebrew bin folder to the $PATH.

• Go to TextMate's Preferences (Cmd+,)
• Go to "Advanced", then "Shell Variables"
• Edit the PATH variable, and add ":/path/to/homebrew/bin"

For example, if you have homebrew installed in ~/.homebrew then you might add :/Users/drnic/.homebrew/bin

Save a dodgy Ruby file and see the beautifully helpful syntax message.