How to load libraries into controllers and how to dynamically load app

Question

I am new to Rails. I came from a Codeigniter background. I am having a hard time finding resources on Rails 3.0 for beginners. I read my new Rails book but am still confused about a few things.

How do I include my libraries or helpers into a controller? Do I use an "include" or "require"?

The 2nd question is how do I dynamically load plugins? Let say I have 1,000 plugins. I don't want them to be all initialized. Is there a way to controller which plugin are initialized from controllers?

Answer 1

When your app starts it will run all the scripts in yourapp/config/initializers, there you can add some stuff that you want always present.

in yourapp/config/application.rb you can add

config.autoload_paths += %W(#{config.root}/lib)

inside the class Application declaration. Then any time you use a class it doesn't know about like SomeNewClass.new "param" rails will try to autoload yourapp/lib/some_new_class.rb

As for your second question I don't know. I have never used more than a few plugins.

Answer 2

Unlike PHP (Codeigniter), in Ruby require and include are very different in behaviour. require loads a given path (somewhat like PHP) while include is usually used to include a Module in a Class.

require is a method from Kernel while include acts more like an object of class Class. Try -

Kernel.respond_to? :require
include.is_a? Class

Before jumping on Rails, I suggest you to read on Ruby. I suggest this book and http://en.wikibooks.org/wiki/Ruby_programming_language.

For Ruby on Rails, I recommend -

1. http://guides.rubyonrails.org/
2. http://api.rubyonrails.org/

For 2nd question, I guess, initialising plugins is part of Rails' initialisation process, so it probably can not be selective (but I'm not sure). See http://ryanbigg.com/guides/initialization.html for more information.

The most easiest way to avoid a plugin from being initialised is to put it in some path which is not in Rails' (auto)load_paths, say vendor/extensions and require them in controllers when needed using

require "vendor/extensions/example-plugin/lib/example-plugin"

However, I recommend against it and suggest to wait until your plugin count reaches 1000/10. :)