X-Git-Url: https://git.distorted.org.uk/~mdw/lisp/blobdiff_plain/d7d819976cb5d84766bffd2c5272c86203687ee9..d6caa73bc6253f7a0461406a939865a207bad7c8:/mdw-base.lisp

diff --git a/mdw-base.lisp b/mdw-base.lisp
index 2c1a79c..a41b685 100644
--- a/mdw-base.lisp
+++ b/mdw-base.lisp
@@ -135,6 +135,17 @@
        t)
     (t nil)))
 
+(defmacro defconstant* (name value &key doc test)
+  "Define a constant, like `defconstant'.  The TEST is an equality test used
+   to decide whether to override the current definition, if any."
+  (let ((temp (gensym)))
+    `(eval-when (:compile-toplevel :load-toplevel :execute)
+       (let ((,temp ,value))
+	 (unless (and (boundp ',name)
+		      (funcall ,(or test ''eql) (symbol-value ',name) ,temp))
+	   (defconstant ,name ,value ,@(and doc (list doc))))
+	 ',name))))
+
 (declaim (ftype (function nil ()) slot-unitialized))
 (defun slot-uninitialized ()
   "A function which signals an error.  Can be used as an initializer form in