Question

Some times I see code like this:

module Elite

    module App
        def app
            'run app'
        end
    end

    module Base
        def base
            'base module'
        end
    end

    class Application
        include Elite::Base #Include variant A
        include ::Elite::App #Include variant B

        def initialize(str=nil) 
            puts "Initialized with #{str}"
            puts "Is respond to base?: #{base if self.respond_to?(:base)}"
            puts "Is respond to app?: #{app if self.respond_to?(:app)}"

        end
    end

    class Store < ::Elite::Application

        def initialize(str=nil)
            super #Goes to Application init
        end
    end
end

elite = Elite::Store.new(:hello)

But I don’t understand what’s different between class Store < ::Elite::Application and class Store < Elite::Application or include Elite::Base and include ::Elite::App
Is it only coding style, or ìs it something different?

What does :: do before Class/Module? :: clean namespace (module name) for class/module? Because class Store < Application works, but this doesn’t: class Store < ::Application. Please tell me what’s the difference… Thanks!

Answer 1

‘::’ is the base(global) scope operator.

So ‘::Application’ references the base Application where as ‘Application’ references Application in the current scope.

For example

class Application # Class 1
end

class Smile
  class Application # Class 2
  end

  ::Application # references class 1
  Application # references class 2 (The application in my current scope)
end