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common-lispclosslot

Initializing slots based on other slot values in Common Lisp Object System class definitions

In my class definition, I want to initialize one slot based on the value of another slot. Here is the sort of thing I would like to do:

(defclass my-class ()
  ((slot-1 :accessor my-class-slot-1 :initarg slot-1)
   (slot-2 :accessor my-class-slot-2 :initform (list slot-1))))

However this doesn't compile:

1 compiler notes:

Unknown location:
  warning: 
    This variable is undefined:
      SLOT-1

  warning: 
    undefined variable: SLOT-1
    ==>
      (CONS UC-2::SLOT-1 NIL)


Compilation failed.

Is there a way to do this?

Solution

  • Use initialize-instance :after documented here