More improvements to virtual slot access

[clg] / gffi / virtual-slots.lisp

diff --git a/gffi/virtual-slots.lisp b/gffi/virtual-slots.lisp
index b57082c562b161a77b53391b19bab25714c9174e..6551210bf1bb6c5d1151afba26986db29fdc0102 100644 (file)
--- a/gffi/virtual-slots.lisp
+++ b/gffi/virtual-slots.lisp
@@ -20,7 +20,7 @@
 ;; TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
 ;; SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 
-;; $Id: virtual-slots.lisp,v 1.2 2006-08-16 11:02:45 espen Exp $
+;; $Id: virtual-slots.lisp,v 1.3 2006-08-16 12:09:03 espen Exp $
 
 (in-package "GFFI")
 
@@ -58,12 +58,21 @@ (defclass effective-special-slot-definition (standard-effective-slot-definition)
 (defclass virtual-slots-object (standard-object)
   ())
 
-
+(defgeneric slot-readable-p (slotd))
+(defgeneric slot-writable-p (slotd))
 (defgeneric compute-slot-reader-function (slotd &optional signal-unbound-p))
 (defgeneric compute-slot-boundp-function (slotd))
 (defgeneric compute-slot-writer-function (slotd))
 (defgeneric compute-slot-makunbound-function (slotd))
 
+(defmethod slot-readable-p ((slotd standard-effective-slot-definition))
+  (declare (ignore slotd))
+  t)
+
+(defmethod slot-writable-p ((slotd standard-effective-slot-definition))
+  (declare (ignore slotd))
+  t)
+
 
 #+clisp
 (defmethod slot-definition-type ((slotd t))
@@ -87,6 +96,9 @@ (defmethod effective-slot-definition-class ((class virtual-slots-class) &rest in
    (t (call-next-method))))
 
 
+(defmethod slot-readable-p ((slotd effective-virtual-slot-definition))
+  (slot-boundp slotd 'getter))
+
 (define-condition unreadable-slot (cell-error)
   ((instance :reader unreadable-slot-instance :initarg :instance))
   (:report (lambda (condition stream)
@@ -95,45 +107,50 @@ (define-condition unreadable-slot (cell-error)
              (unreadable-slot-instance condition)))))
 
 (defmethod compute-slot-reader-function :around ((slotd effective-virtual-slot-definition) &optional (signal-unbound-p t))
-  (let ((reader-function (call-next-method)))
-    (cond
-     ((not signal-unbound-p) reader-function)
-
-     ;; An explicit boundp function has been supplied
-     ((slot-boundp slotd 'boundp) 
-      (let ((unbound-value (slot-value slotd 'boundp)))
-       #'(lambda (object)
-           (let ((value (funcall reader-function object)))
-             (if (eq value unbound-value)
-                 (slot-unbound (class-of object) object (slot-definition-name slotd))
-               value)))))
-
-     ;; A type unbound value exists
-     ((let ((unbound-method (find-applicable-type-method 'unbound-value 
-                            (slot-definition-type slotd) nil)))
-       (when unbound-method
-         (let ((unbound-value (funcall unbound-method (slot-definition-type slotd))))
-           #'(lambda (object)
-               (let ((value (funcall reader-function object)))
-                 (if (eq value unbound-value)
-                     (slot-unbound (class-of object) object (slot-definition-name slotd))
-                   value)))))))
-
-     ((let ((boundp-function (compute-slot-boundp-function slotd)))
-       #'(lambda (object)
-           (if (funcall boundp-function object)
-               (funcall reader-function object)
-             (slot-unbound (class-of object) object (slot-definition-name slotd)))))))))
+  (if (not (slot-readable-p slotd))
+      #'(lambda (object)
+         (error 'unreadable-slot :name (slot-definition-name slotd) :instance object))
+    (let ((reader-function (call-next-method)))
+      (cond
+       ;; Don't create an wrapper to signal unbound value
+       ((not signal-unbound-p) reader-function)
+       
+       ;; An explicit boundp function has been supplied
+       ((slot-boundp slotd 'boundp) 
+       (let ((unbound-value (slot-value slotd 'boundp)))
+         #'(lambda (object)
+             (let ((value (funcall reader-function object)))
+               (if (eq value unbound-value)
+                   (slot-unbound (class-of object) object (slot-definition-name slotd))
+                 value)))))
+       
+       ;; A type unbound value exists
+       ((let ((unbound-method (find-applicable-type-method 'unbound-value 
+                              (slot-definition-type slotd) nil)))
+         (when unbound-method
+           (let ((unbound-value (funcall unbound-method (slot-definition-type slotd))))
+             #'(lambda (object)
+                 (let ((value (funcall reader-function object)))
+                   (if (eq value unbound-value)
+                       (slot-unbound (class-of object) object (slot-definition-name slotd))
+                     value)))))))
+       
+       ((let ((boundp-function (compute-slot-boundp-function slotd)))
+         #'(lambda (object)
+             (if (funcall boundp-function object)
+                 (funcall reader-function object)
+               (slot-unbound (class-of object) object (slot-definition-name slotd))))))))))
 
 (defmethod compute-slot-reader-function ((slotd effective-virtual-slot-definition) &optional signal-unbound-p)
   (declare (ignore signal-unbound-p))
-  (if (slot-boundp slotd 'getter)
-      (slot-value slotd 'getter)
-    #'(lambda (object)
-       (error 'unreadable-slot :name (slot-definition-name slotd) :instance object))))
+  (slot-value slotd 'getter))
 
 (defmethod compute-slot-boundp-function ((slotd effective-virtual-slot-definition))
   (cond
+   ;; Non readable slots are not bound per definition
+   ((not (slot-readable-p slotd))
+    #'(lambda (object) (declare (ignore object)) nil))
+
    ;; An explicit boundp function has been supplied
    ((slot-boundp slotd 'boundp) (slot-value slotd 'boundp))
    
@@ -156,6 +173,9 @@ (defmethod compute-slot-boundp-function ((slotd effective-virtual-slot-definitio
    ;; Slot has no unbound state
    (#'(lambda (object) (declare (ignore object)) t))))
 
+(defmethod slot-writable-p ((slotd effective-virtual-slot-definition))
+  (slot-boundp slotd 'setter))
+
 (define-condition unwritable-slot (cell-error)
   ((instance :reader unwritable-slot-instance :initarg :instance))
   (:report (lambda (condition stream)
@@ -163,22 +183,35 @@ (define-condition unwritable-slot (cell-error)
              (cell-error-name condition)
              (unwritable-slot-instance condition)))))
 
+(defmethod compute-slot-writer-function :around ((slotd effective-virtual-slot-definition))
+  (if (not (slot-writable-p slotd))
+      #'(lambda (value object)
+         (declare (ignore value))
+         (error 'unwritable-slot :name (slot-definition-name slotd) :instance object))
+    (call-next-method)))
+
 (defmethod compute-slot-writer-function ((slotd effective-virtual-slot-definition))
-  (if (slot-boundp slotd 'setter)
-      (slot-value slotd 'setter)
-    #'(lambda (value object)
-       (declare (ignore value))
-       (error 'unwritable-slot :name (slot-definition-name slotd) :instance object))))
+  (slot-value slotd 'setter))
+
+(define-condition slot-can-not-be-unbound (cell-error)
+  ((instance :reader slot-can-not-be-unbound-instance :initarg :instance))
+  (:report (lambda (condition stream)
+            (format stream "~@<The slot ~S in the object ~S can not be made unbound.~@:>"
+             (cell-error-name condition)
+             (slot-can-not-be-unbound-instance condition)))))
 
 (defmethod compute-slot-makunbound-function ((slotd effective-virtual-slot-definition))
   (cond
+   ((not (slot-writable-p slotd))
+    #'(lambda (object)
+       (error 'unwritable-slot :name (slot-definition-name slotd) :instance object)))
    ((slot-boundp slotd 'makunbound) (slot-value slotd 'makunbound))
    ((slot-boundp slotd 'unbound)
     #'(lambda (object)
        (funcall (slot-value slotd 'writer-function) (slot-value slotd 'unbound) object)))
    (t
     #'(lambda (object)
-       (error 'unwritable-slot :name (slot-definition-name slotd) :instance object)))))
+       (error 'slot-can-not-be-unbound :name (slot-definition-name slotd) :instance object)))))
 
 
 #-clisp