a value to use instead (on an ongoing basis).
the store-value
restart is generally used by handlers
trying to recover from errors of types such as cell-error
or type-error
, which may wish to supply a replacement datum to
be stored permanently.
(defun type-error-auto-coerce (c) (when (typep c 'type-error) (let ((r (find-restart 'store-value c))) (handler-case (let ((v (coerce (type-error-datum c) (type-error-expected-type c)))) (invoke-restart r v)) (error ()))))) → TYPE-ERROR-AUTO-COERCE (let ((x 3)) (handler-bind ((type-error #'type-error-auto-coerce)) (check-type x float) x)) → 3.0
Section 9.1.4.2 (Restarts), Section 9.1.4.2.2 (Interfaces to Restarts), invoke-restart, store-value (function), ccase, check-type, ctypecase, use-value (function and restart)