Rails -Engines

Engines can be considered miniature applications that provide functionality to their host applications. A Rails application is actually just a "supercharged" engine, with the Rails::Application class inheriting a lot of its behavior from Rails::Engine.

Engines are the reusable rails applications/plugins. It works like a Gem. Famous engines are Device, Spree gems which can be integrated with rails applications easily.

Famous examples are

Generating simple blog engine

rails plugin new [engine name] --mountable

Famous engines examples are

Device (opens new window) (authentication gem for rails)

Spree (opens new window) (Ecommerce)

Syntax

• rails plugin new [engine name] --mountable

Parameters

Parameters	Purpose
--mountable	option tells the generator that you want to create a "mountable" and namespace-isolated engine
--full	option tells the generator that you want to create an engine, including a skeleton structure

Remarks

Engines are very good options for creating reusable plugin for rails application