X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~mdw/git/lisp/blobdiff_plain/0ff9df03bb54ba792cefa551face51748ae34259..b3bc37457df55c92cabc8aeeb42bc67d3fb8af12:/mdw-base.lisp

diff --git a/mdw-base.lisp b/mdw-base.lisp
index cde1d7a..6b235f5 100644
--- a/mdw-base.lisp
+++ b/mdw-base.lisp
@@ -179,21 +179,26 @@ (compile-time-defun do-case2-like (kind vform clauses)
        (,kind ,scrutinee
 	 ,@(mapcar (lambda (clause)
 		     (destructuring-bind
-			 (cases (&optional var) &rest forms)
+			 (cases (&optional varx vary) &rest forms)
 			 clause
 		       `(,cases
-			 ,@(if var
-			       (list `(let ((,var ,argument)) ,@forms))
+			 ,@(if varx
+			       (list `(let ((,(or vary varx) ,argument)
+					    ,@(and vary
+						   `((,varx ,scrutinee))))
+				        ,@forms))
 			       forms))))
 		   clauses)))))
 
 (defmacro case2 (vform &body clauses)
   "VFORM is a form which evaluates to two values, SCRUTINEE and ARGUMENT.
-   The CLAUSES have the form (CASES ([VAR]) FORMS...), where a standard
-   `case' clause has the form (CASES FORMS...).  The `case2' form evaluates
-   the VFORM, and compares the SCRUTINEE to the various CASES, in order, just
-   like `case'.  If there is a match, then the corresponding FORMs are
-   evaluated with VAR (if specified) bound to the value of ARGUMENT."
+   The CLAUSES have the form (CASES ([[SCRUVAR] ARGVAR]) FORMS...), where a
+   standard `case' clause has the form (CASES FORMS...).  The `case2' form
+   evaluates the VFORM, and compares the SCRUTINEE to the various CASES, in
+   order, just like `case'.  If there is a match, then the corresponding
+   FORMs are evaluated with ARGVAR bound to the ARGUMENT and SCRUVAR bound to
+   the SCRUTINEE (where specified).  Note the bizarre defaulting behaviour:
+   ARGVAR is less optional than SCRUVAR."
   (do-case2-like 'case vform clauses))
 
 (defmacro ecase2 (vform &body clauses)