CODEWITHSUNDEEP
ruby-on-railsruby-on-rails-3ruby-on-rails-3.1
Bryce
Bryce

Reputation: 2872

Rails convention confusion for altering config files

So, I'm not having a problem so much as I am confused by two different conventions that I see used around the web for changing the Rails config files.

Specifically, I see these two statements used often:

config.autoload_paths << "#{Rails.root}/app/arbitrary"
config.autoload_paths += %W(#{config.root}/app/arbitrary)
config.autoload_paths += Dir["#{config.root}/app/arbitrary/**/"]

First, is there any difference n using the << operator vs the += operator? Second, is it considered a better practice to use Rails.root as opposed to config.root?

Can some of these conventions only be used in certain combinations? I just hate not knowing something so seemingly basic.

Upvotes: 3

Views: 70

Answers (2)

moritz
moritz

Reputation: 25757

<< adds a single value while += adds an array of values. The %w(...) notation is just a shortcut for an array of strings.

Check the source for the Rails.root method: https://github.com/rails/rails/blob/master/railties/lib/rails.rb#L83

so it uses config.root anyhow because

Rails.application.config == Rails.configuration

evaluates to true. This is also the object you get passed for the configure blocks in config/application.rb and config/environments/ files.

Upvotes: 0

Yanhao
Yanhao

Reputation: 5294

difference between << and +=

config.autoload_paths is an Array. For an Array object, << push ONE object to the array, while + joins two array to create a new array. So if you only have one object to be appended to the existing array, << is preferred for performance because no new object will be created. If you want to append another array to the existing array, you have to use +.

Yo know, a1 =+ a2 is equal to a1 = a1 + a2.

Rails.root v.s. config.root

Rails.root is just the root of Rails app. If config.root is used in a Rails app, it should be same as Rails.root. But it can also be used in Engines, where it will be the Engine's root. If config.root is used in a Rails app, you may not have to change it to use the app as an Engine.

Upvotes: 1

Related Questions