Chapter 17. Engines

This chapter covers

  • The importance of engines for Rails 3
  • Building a new engine and exploring the base
  • Using behavior-driven development to develop an engine
  • Releasing the engine as a gem
  • Integrating an engine with an app

Engines are a new feature for Rails 3.[1] They are effectively miniature applications that provide additional functionality to an application, and they function in much the same way as an application.

1 Although in previous versions they were supported by a plugin written by the community: https://github.com/lazyatom/engines.

Back in chapter 6, you used the Devise gem, which itself is an engine. Other engines include the RailsAdmin[2] and forem[3] engines.

2http://github.com/sferik/rails_admin ...

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