Plaster

common-lisp
;;;; metalock.lisp (in-package #:metalock) (defclass metalock (sb-mop:standard-class) ((locks :type list :accessor locks))) (defmethod sb-mop:validate-superclass ((class metalock) (metaclass standard-class)) t) (defmethod sb-mop:validate-superclass ((class standard-class) (metaclass metalock)) t) (defparameter *lock* (bt:make-lock)) (defmethod sb-mop:slot-value-using-class :around ((class metalock) object slotd) (bt:with-lock-held (*lock*) (print "lock held") (let ((val (call-next-method))) (print "lock dropped") val))) (defun slot-names-to-lock-alist (slot-names) (check-type slot-names list) (mapcar (lambda (name) (cons name (bt:make-lock))) slot-names)) (defmethod sb-mop:effective-slot-definition-class ((class metalock) &rest _) (declare (ignore _)) (find-class 'sb-mop:effective-slot-definition )) (defmethod sb-mop:direct-slot-definition-class ((class metalock) &rest _) (declare (ignore _)) (find-class 'sb-mop:standard-direct-slot-definition)) (defmethod sb-mop:compute-slots ((class metalock)) (let* ((normal-slots (call-next-method)) (slot-names (mapcar #'sb-mop:slot-definition-name normal-slots)) (slot-names-lock-alist (slot-names-to-lock-alist slot-names))) (cons (make-instance 'sb-mop:standard-effective-slot-definition :name 'slot-locks ;;:initform `',slot-names-lock-alist :initfunction #'(lambda () slot-names-lock-alist)) normal-slots))) (defclass locked-object () ((arr :initform "oof" :accessor arr-access)) (:metaclass metalock))