Is there a difference between self.current_user and @current_user?

I am looking at this ruby code and they make reference to:

@current_user

and

self.current_user

what is the difference?

http://code.goog开发者_C百科le.com/p/openplaques/source/browse/trunk/www/lib/authenticated_system.rb

@current_user is an instance variable. self.current_user calls the method on line 10 that returns that instance variable, first populating it if it is currently nil.

@current_user accesses the actual property of the object whereas self.current_user is calling the current_user method on self.

This means you could do something like this:

def current_user
  @current_user.first_name
end

So now accessing @current_user will still give you the property but self.current_user will give you back the first name only.

In your specific example they are using object caching to set the @current_user property only the first time it is accessed. This means that if @current_user is nil, it'll do (login_from_session || login_from_basic_auth || login_from_cookie) otherwise it'll just return the existing object without reinitializing it.

@current_user

dereferences the instance variable called @current_user.

self.current_user

sends the message :current_user to self.