Let's not add_bundler_dependencies anymore

The article I published about using Bundler to manage your gem’s gem dependencies turned out a bit different than I thought. I started writing it because I had a problem with Bundler’s add_bundler_dependencies method and I wanted to propose a better way to handle this.

So I went to Bundler’s amazing little website to read up the nasty feature, but it was gone. After looking around for a second, I found the new “Using Bundler with Rubygem gemspecs” page and realized a lot had changed since everybody got excited about add_bundler_dependencies at Railsconf.

I ended up writing a cheerful article about how awesome Bundler was, since my biggest annoyance had been destroyed. Now, a couple of weeks later, this article about add_bundler_dependencies started to get mentioned again. Please allow me to explain why I think you should stop using it.

Why?

If you don’t know, add_bundler_dependencies allows you to make your .gemspec get its dependencies from your Gemfile:

# .gemspec
require 'bundler'
Gem::Specification.new do |s|
  s.add_bundler_dependencies
end

A very convenient way not to have to specify your dependencies twice, right? The problem with this is that you just added Bundler to your gem’s dependencies.

This feels totally backwards, since the .gemspec file should be the one specifying Gem dependencies. If you ask me, getting them from the Gemfile instead and adding a dependency is wrong. Bundler should only be needed when you want to do something with the Gemfile, the .gemspec — and the rest of the gem — should work without it.

Gemfiles reading .gemspecs

The new implementation turns this all around and allows you to let your Gemfile read dependencies from your .gemspec, so you don’t need Bundler to install it anymore. It’s a matter of simply throwing gemspec into your Gemfile:

# Gemfile
gemspec

Please, let’s start using that one now. It’s prettier, it makes more sense and there’s a reason add_bundler_dependencies isn’t mentioned on the Bundler website anymore.

What do you think about a deprecation warning when still using add_bundler_dependencies? @wycats? @carllerche? Anyone? Oh, it’ll throw a deprecation warning too.