Cool Example

• Object-oriented programming with closures

• Invented by Guy Steele in 1976

(defun make-account (&key (balance 0.0))

"Create an ACCOUNT object with one slot, BALANCE"

#'(lambda (message &rest args)

(case message

;; Object supports three methods or messages

(:deposit (incf balance (car args)))

(:withdraw (decf balance (car args)))

(:balance balance))))

(defun send (object message &rest args)

(apply object message args))

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