dot notation for slot-access

Author: lispm

Diff for: dot-slot-value-access.lisp

@@ -0,0 +1,37 @@
+;;; Dot notation for slot values
+
+;;; Rainer Joswig, [email protected], 2012
+
+
+; Example
+;
+; #!turtle.drawing.pen-down-p
+;
+;  expands to
+;
+; (slot-value (slot-value turtle 'drawing) 'pen-down-p)
+;
+
+
+(defun make-calls (string)
+  (let ((symbols (reverse
+                  (mapcar (lambda (string)
+                            (intern string))
+                          (split-sequence '(#\.) string)))))
+    (labels ((nest (list)
+               (if (not (cddr list))
+                   `(slot-value ,(second list) ',(first list))
+                 `(slot-value ,(nest (cdr list))
+                              ',(first list)))))
+      (nest symbols))))
+
+(defun read-instance-slot-value (stream subchar arg)
+  (declare (ignore subchar arg))
+  (make-calls (symbol-name (let ((*readtable* (copy-readtable nil)))
+                             (read stream)))))
+
+(set-dispatch-macro-character
+  #\# #\!
+  #'read-instance-slot-value)
+
+