Dependencies

A simple way to express, manage and require your dependencies in Ruby.

Dependencies allows you to declare the list of libraries your application needs with a simple, readable syntax. It comes with a handy command line tool for inspecting and vendoring your dependencies.

Declare your dependencies in a dependencies file in the root of your project:

rack ~> 1.0
sinatra
webrat (test) git://github.com/brynary/webrat.git
quietbacktrace ~> 0.1
contest ~> 0.1 (test)
haml ~> 2.0
rack-test 0.3 (test)
faker ~> 0.3
spawn ~> 0.1
ohm git://github.com/soveran/ohm.git

Now you can try the dep command line tool to check your dependencies:

$ dep list

You can specify an environment to see if requirements are met:

$ dep list test

The above is RACK_ENV-aware.

In order to vendor a library you're using, simply:

$ dep vendor haml

If the dependency is expressed with a version number, it will be vendored using gem unpack. Otherwise, it will try to clone from a Git repository.

It's common to vendor everything when you start a new project. Try this:

$ dep vendor --all

Dependencies doesn't assume you want to use RubyGems, so you're in charge of requiring it before requiring dependencies (in Ruby 1.9 you're cornered – there's no way out).

# init.rb
require "rubygems"
require "dependencies"

That will work as long as RubyGems is available and you have Dependencies installed. If a dependency is not found in ./vendor, a call to #gem will be made.

Another option is to vendor Dependencies itself:

# init.rb
require "vendor/dependencies/lib/dependencies"

After that, all your lib directories below ./vendor will be available in the $LOAD_PATH.

Additionally, Dependencies will leave your ./lib in the $LOAD_PATH.

1. Documentation. It's a text file any team member can read to see what the project depends on.
2. Early failure. If a dependency is not met, the program terminates with a polite message inviting you to install the missing dependencies.
3. Vendorability (™). Easily vendor everything for self-contained applications.
4. Simplicity. It's a very lightweight tool. It won't do everything, but it's simple and works very well for us.

$ sudo gem install dependencies

Copyright (c) 2009 Damian Janowski

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

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