unbound-value-indicator |
| [Constant] |
Purpose
Represent an unbound value.
Package :gbbopen-tools
Module :gbbopen-tools
Value type A keyword symbol
Value :---unbound---
See also
define-unit-class
Example
Define a slot-reader function that returns the value of
my-slot
(defun safe-my-slot-of (instance) (if (slot-bound-p instance 'my-slot) (slot-value instance 'my-slot) unbound-value-indicator))
The GBBopen Project
unbound-value-indicator |