Question

I have seen this in initializers in rails (config/initializers/foo.rb)

module foo
     module bar
         def self.biz
            @blahblah = "what am i"
         end
     end
end

How is self used?
What instance is @blahblah being attached to?

Answer 1

self in ruby is a method on the class itself, not an object.

So if you have

class SuperHero
  def self.awesome?
    true
  end
end

Then you can call SuperHero.awesome?

In your example, you have added a class method to Foo::Bar

module Foo
  module Bar
    def self.biz
      @blahblah = "what am i"
    end
  end
end

So you can call .biz on the class (which is a module Bar in the Foo module)

Foo::Bar.biz
 => "what am i"