From: Dave Burt <dave@...>
Date: 2006-04-03T21:28:46+09:00
Subject: Re: self.some_attribute vs @some_attribute

Fred wrote:
>   def crypt_unless_empty
>     if password(true).empty?
>       user = self.class.find(self.id)
>       self.password = user.password
>     else
>       write_attribute "password", self.class.sha1(password(true))
>       @password = nil
>     end
>   end
> 
> is there any practical reason to use sometimes self.password and 
> sometimes @password? I thought they were synonyms...

self.password = ... # calls the method "password="

It's a method call. You might assume from the name it sets @password, 
but it may do other stuff as well (e.g. checks, or in this case, encrypt 
the given password string).

In an ActiveRecord subclass (as this appears to be) password=(foo) is a 
method that just calls write_attribute("password", foo), simply setting 
the password attribute of the active record. There's no @password 
involved, only @attributes["password"].

Of course, this method can be overridden, and it probably is in the 
class you're looking at. Look for the line beginning "def password=" for 
more clues.

Cheers,
Dave