Managing Gems
Gems are packages and the default format for sharing Ruby programs and libraries (though you could, theoretically, use it for anything).
Gems are shared through the package manager RubyGems.org. You are free to publish your own gems to the repository and RubyGems will make them available through their API.
The API can be accessed through the gem client. If you’re on OS X you will probably have it already. You can verify by typing gem in the command line.
Installing gems
To install the Sass gem you’d write:
$ gem install sass
If if asks for your password, you need to use sudo to install. Always try to avoid using sudo but for some reason Gems really enjoy sudo and it will not cause you any trouble.
$ sudo gem install sass
This will look up Sass on RubyGems.org, find the newest released version and install it globally on your system. If you wanted a specific version you would write:
$ gem install sass -v 3.3.0.rc.2
Sometimes the early/alpha/prerelease versions of Gems are also published and available under the --pre flag:
$ gem install sass --pre
If you want to get rid of a gem, use gem uninstall sass.
Different gems for different projects
As soon as have more than one project chances are that they require different versions of the same gem. As gems are installed globally you will have a problem. If you work together with others it is very likely that they have a different setup.
To avoid these conflicts you want to manage gems on a project level. You do this using Bundler. You define what you need in a Gemfile (with uppercase ‘G’ and no file extension). The Gemfile needs to be in the root of your project. This is the same concept as NPM + packages.json and Bower + bower.json.
This way you define specifically which gems and versions your project needs and everything is defined in the Gemfile which makes it easy to share across systems (your co-workers).
Here’s an example of a Gemfile:
source 'http://rubygems.org' gem "sass", "~> 3.3.0.rc.2" gem "compass", "~> 0.13.alpha.12" gem "susy", "~> 2.0.0.alpha.5" gem "sass-css-importer" gem "breakpoint", "~> 2.2.0"
To install all this, you need to install Bundler.
$ gem install bundle
“If any of the needed gems are already installed, Bundler will use them. After installing any needed gems to your system, bundler writes a snapshot of all of the gems and versions that it installed to Gemfile.lock.”
Making Compass understand
This one is easily missed. By default, Compass will use the global gems and not the ones defined in your Gemfile. To make Compass use them, you have to run Compass thorugh bundler like so:
bundle exec compass watch
Making Compass understand through Grunt
Using grunt-contrib-compass you tell Compass to run its commands through bundler like this:
```compass: { options: { // Makes use of the local Gemfile bundleExec: true, // … where we have defined the following: require: [‘breakpoint’, ‘susy’, ‘sass-css-importer’]
………… more options are normally here
}
}```