eieio defclass evaluate :initform value

[Joe Riel]

According to the info page for eieio for Emacs 23, one
could do

(defclass foo-class
   ((bar :initform (lambda () my-var)
         :type string)))

When make-instance was called, the lambda expression
for :initform would be evaluated and the expression
assigned to my-var would be used for the slot bar.

The info page for eieio Emacs 24 does not mention this 
functionality and testing shows it no longer exists.

Is there nice way, in 24, to create a class with an :initform
that, upon instantiation, evaluates to the value of a variable?
  

-- 
Joe Riel