What does :: do?

Question

I have some inherited code that I am modifying. However, I am seeing something strange(to me).

I see some code like this:

::User.find_by_email(params         


        

Answer 1

Ruby uses (among other things) lexical scoping to find constant names. For example, if you have this code:

module Foo
  class Bar
  end

  def self.get_bar
    Bar.new
  end
end

class Bar
end

The Foo.get_bar returns an instance of Foo::Bar. But if we put :: in front of a constant name, it forces Ruby to only look in the top level for the constant. So ::Bar always refers the top-level Bar class.

You will run into situations in Ruby where the way your code is being run will force you to use these 'absolute' constant references to get to the class you want.