Class Variables in activerecord

If you are asking about actual class and class instance variables
here's a brief explanation. If you're talking about variables that
show up in view templates or somewhere else then please be more
descriptive with your question.

Class variables in ruby persist throughout a whole class hierarchy.

   class A
      @@a = 1

      def self.a ; @@a ; end
   end

   A.a # => 1

   class B < A
      @@a = 2
   end

   A.a # => 2
   B.a # => 2

Class instance variables on the other hand exist in the context of a
single class definition.

   class C
      @c = 1
      def self.c ; @c ; end
   end

  C.c # => 1

  class D < C
       @c = 2
  end

  C.c # => 1
  D.c # => 2

Zach