X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~mdw/git/clg/blobdiff_plain/a2ff61db79afe32e37e437266af9fc36eaa5995c..5de2b5f6a587aff7590db74f3aa7eb622cd8904c:/glib/gobject.lisp

diff --git a/glib/gobject.lisp b/glib/gobject.lisp
index f888cc6..59e8fcc 100644
--- a/glib/gobject.lisp
+++ b/glib/gobject.lisp
@@ -1,21 +1,26 @@
-;; Common Lisp bindings for GTK+ v2.0
-;; Copyright (C) 2000-2001 Espen S. Johnsen <esj@stud.cs.uit.no>
+;; Common Lisp bindings for GTK+ v2.x
+;; Copyright 2000-2005 Espen S. Johnsen <espen@users.sf.net>
 ;;
-;; This library is free software; you can redistribute it and/or
-;; modify it under the terms of the GNU Lesser General Public
-;; License as published by the Free Software Foundation; either
-;; version 2 of the License, or (at your option) any later version.
+;; Permission is hereby granted, free of charge, to any person obtaining
+;; a copy of this software and associated documentation files (the
+;; "Software"), to deal in the Software without restriction, including
+;; without limitation the rights to use, copy, modify, merge, publish,
+;; distribute, sublicense, and/or sell copies of the Software, and to
+;; permit persons to whom the Software is furnished to do so, subject to
+;; the following conditions:
 ;;
-;; This library is distributed in the hope that it will be useful,
-;; but WITHOUT ANY WARRANTY; without even the implied warranty of
-;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
-;; Lesser General Public License for more details.
+;; The above copyright notice and this permission notice shall be
+;; included in all copies or substantial portions of the Software.
 ;;
-;; You should have received a copy of the GNU Lesser General Public
-;; License along with this library; if not, write to the Free Software
-;; Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+;; THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+;; EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+;; MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+;; IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+;; CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+;; TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+;; SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 
-;; $Id: gobject.lisp,v 1.22 2004-11-12 14:24:17 espen Exp $
+;; $Id: gobject.lisp,v 1.49 2006-02-19 22:24:37 espen Exp $
 
 (in-package "GLIB")
 
@@ -23,25 +28,33 @@ (in-package "GLIB")
 ;;;; Metaclass used for subclasses of gobject
 
 (eval-when (:compile-toplevel :load-toplevel :execute)
+;;   (push :debug-ref-counting *features*)
   (defclass gobject-class (ginstance-class)
-    ())
+    ((instance-slots-p :initform nil
+      :documentation "Non NIL if the class has slots with instance allocation")))
 
-  (defmethod validate-superclass ((class gobject-class)
-				(super pcl::standard-class))
+  (defmethod validate-superclass ((class gobject-class) (super standard-class))
 ;  (subtypep (class-name super) 'gobject)
     t))
 
 (defclass direct-property-slot-definition (direct-virtual-slot-definition)
   ((pname :reader slot-definition-pname :initarg :pname)
-   (readable :initform t :reader slot-readable-p :initarg :readable)
-   (writable :initform t :reader slot-writable-p :initarg :writable)
-   (construct :initform nil :initarg :construct)))
+   (readable :reader slot-readable-p :initarg :readable)
+   (writable :reader slot-writable-p :initarg :writable)
+   (construct-only :initarg :construct-only :reader construct-only-property-p)))
 
 (defclass effective-property-slot-definition (effective-virtual-slot-definition)
   ((pname :reader slot-definition-pname :initarg :pname)
    (readable :reader slot-readable-p :initarg :readable)
    (writable :reader slot-writable-p :initarg :writable)
-   (construct :initarg :construct)));)
+   (construct-only :initarg :construct-only :reader construct-only-property-p)))
+
+(defclass direct-user-data-slot-definition (direct-virtual-slot-definition)
+  ())
+
+(defclass effective-user-data-slot-definition (effective-virtual-slot-definition)
+  ())
+
 
 (defbinding %object-ref () pointer
   (location pointer))
@@ -49,6 +62,28 @@ (defbinding %object-ref () pointer
 (defbinding %object-unref () nil
   (location pointer))
 
+#+glib2.8
+(progn
+  (define-callback toggle-ref-callback nil
+      ((data pointer) (location pointer) (last-ref-p boolean))
+    #+debug-ref-counting
+    (if last-ref-p
+	(format t "Object at 0x~8,'0X has no foreign references~%" (sap-int location))
+      (format t "Foreign reference added to object at 0x~8,'0X~%" (sap-int location)))
+    (if last-ref-p
+	(cache-instance (find-cached-instance location) t)
+      (cache-instance (find-cached-instance location) nil)))
+
+  (defbinding %object-add-toggle-ref (location) pointer
+    (location pointer)
+    (toggle-ref-callback callback)
+    (nil null))
+
+  (defbinding %object-remove-toggle-ref (location) pointer
+    (location pointer)
+    (toggle-ref-callback callback)
+    (nil null)))
+
 (defmethod reference-foreign ((class gobject-class) location)
   (declare (ignore class))
   (%object-ref location))
@@ -57,6 +92,16 @@ (defmethod unreference-foreign ((class gobject-class) location)
   (declare (ignore class))
   (%object-unref location))
 
+#+debug-ref-counting
+(progn
+  (define-callback weak-ref-callback nil ((data pointer) (location pointer))
+    (format t "Object at 0x~8,'0X being finalized~%" (sap-int location)))
+  
+  (defbinding %object-weak-ref (location) pointer
+    (location pointer)
+    (weak-ref-callback callback)
+    (nil null)))
+
 
 ; (defbinding object-class-install-param () nil
 ;   (class pointer)
@@ -74,129 +119,227 @@ (defun signal-name-to-string (name)
 (defmethod direct-slot-definition-class ((class gobject-class) &rest initargs)
   (case (getf initargs :allocation)
     (:property (find-class 'direct-property-slot-definition))
+    (:user-data (find-class 'direct-user-data-slot-definition))
     (t (call-next-method))))
 
 (defmethod effective-slot-definition-class ((class gobject-class) &rest initargs)
   (case (getf initargs :allocation)
     (:property (find-class 'effective-property-slot-definition))
+    (:user-data (find-class 'effective-user-data-slot-definition))
     (t (call-next-method))))
 
 (defmethod compute-effective-slot-definition-initargs ((class gobject-class) direct-slotds)
-  (if (eq (most-specific-slot-value direct-slotds 'allocation) :property)
+  (if (eq (slot-definition-allocation (first direct-slotds)) :property)
       (nconc 
        (list :pname (signal-name-to-string 
-		     (most-specific-slot-value direct-slotds 'pname))
-	     :readable (most-specific-slot-value direct-slotds 'readable)
-	     :writable (most-specific-slot-value direct-slotds 'writable)
-	     :construct (most-specific-slot-value direct-slotds 'construct))
+		     (most-specific-slot-value direct-slotds 'pname
+		      (slot-definition-name (first direct-slotds))))
+	     :readable (most-specific-slot-value direct-slotds 'readable t)
+	     :writable (most-specific-slot-value direct-slotds 'writable t)
+	     :construct-only (most-specific-slot-value direct-slotds 
+                              'construct-only nil))
        (call-next-method))
     (call-next-method)))
 
 
+(defvar *ignore-setting-construct-only-property* nil)
+(declaim (special *ignore-setting-construct-only-property*))
+
 (defmethod initialize-internal-slot-functions ((slotd effective-property-slot-definition))
-  (let* ((type (slot-definition-type slotd))
-	 (pname (slot-definition-pname slotd))
-	 (type-number (find-type-number type)))
-    (unless (slot-boundp slotd 'reader-function)
+  (let ((type (slot-definition-type slotd))
+	(pname (slot-definition-pname slotd)))
+    (when (and (not (slot-boundp slotd 'getter)) (slot-readable-p slotd))
       (setf 
-       (slot-value slotd 'reader-function)
-       (if (slot-readable-p slotd)
-	   (let () ;(reader (reader-function (type-from-number type-number))))
-	     #'(lambda (object)
-		 (let ((gvalue (gvalue-new type-number)))
-		   (%object-get-property object pname gvalue)
-		   (unwind-protect
-			(funcall #|reader|# (reader-function (type-from-number type-number))  gvalue +gvalue-value-offset+)
-		     (gvalue-free gvalue t)))))
-	   #'(lambda (value object)
-	       (error "Slot is not readable: ~A" (slot-definition-name slotd))))))
+       (slot-value slotd 'getter)
+       (let ((reader nil))
+	 #'(lambda (object)
+	     (unless reader
+	       (setq reader (reader-function type)))
+	     (let ((gvalue (gvalue-new type)))
+	       (%object-get-property object pname gvalue)
+	       (unwind-protect
+		 (funcall reader  gvalue +gvalue-value-offset+)
+		 (gvalue-free gvalue t)))))))
     
-    (unless (slot-boundp slotd 'writer-function)
+    (when (not (slot-boundp slotd 'setter))
+      (cond
+       ((slot-writable-p slotd)
+	(setf 
+	 (slot-value slotd 'setter)
+	 (let ((writer nil))
+	   #'(lambda (value object)
+	       (unless writer
+		 (setq writer (writer-function type)))
+	       (let ((gvalue (gvalue-new type)))
+		 (funcall writer value gvalue +gvalue-value-offset+)
+		 (%object-set-property object pname gvalue)
+		 (gvalue-free gvalue t)
+		 value)))))
+
+       ((construct-only-property-p slotd)
+	(setf 
+	 (slot-value slotd 'setter)
+	 #'(lambda (value object)
+	     (declare (ignore value object))
+	     (unless *ignore-setting-construct-only-property*
+	       (error "Slot is not writable: ~A" (slot-definition-name slotd)))))))))
+
+  (call-next-method))
+
+(defmethod initialize-internal-slot-functions ((slotd effective-user-data-slot-definition))
+  (let ((slot-name (slot-definition-name slotd)))
+    (unless (slot-boundp slotd 'getter)
       (setf 
-       (slot-value slotd 'writer-function)
-       (if (slot-writable-p slotd)
-	   (let ();; (writer (writer-function (type-from-number type-number)))
-;; 		 (destroy (destroy-function (type-from-number type-number))))
-	     #'(lambda (value object)
-		 (let ((gvalue (gvalue-new type-number)))
-		   (funcall #|writer|# (writer-function (type-from-number type-number)) value gvalue +gvalue-value-offset+)
-		   (%object-set-property object pname gvalue)
-;		   (funcall #|destroy|#(destroy-function (type-from-number type-number)) gvalue +gvalue-value-offset+)
-		   (gvalue-free gvalue t)
-		   value)))
- 	   #'(lambda (value object)
- 	       (error "Slot is not writable: ~A" (slot-definition-name slotd))))))
-    
-    (unless (slot-boundp slotd 'boundp-function)
+       (slot-value slotd 'getter)
+       #'(lambda (object)
+	   (prog1 (user-data object slot-name)))))
+    (unless (slot-boundp slotd 'setter)
       (setf 
-       (slot-value slotd 'boundp-function)
+       (slot-value slotd 'setter)
+       #'(lambda (value object)
+	   (setf (user-data object slot-name) value))))
+    (unless (slot-boundp slotd 'boundp)
+      (setf 
+       (slot-value slotd 'boundp)
        #'(lambda (object)
-	   (declare (ignore object))
-	   t))))
+	   (user-data-p object slot-name)))))
   (call-next-method))
 
+(defmethod shared-initialize :after ((class gobject-class) names &rest initargs)
+  (declare (ignore initargs))
+  (when (some #'(lambda (slotd)
+		  (and
+		   (eq (slot-definition-allocation slotd) :instance)
+		   (not (typep slotd 'effective-special-slot-definition))))
+	      (class-slots class))
+    (setf (slot-value class 'instance-slots-p) t)))
+
+
 
 ;;;; Super class for all classes in the GObject type hierarchy
 
 (eval-when (:compile-toplevel :load-toplevel :execute)
   (defclass gobject (ginstance)
-    ()
+    (#+debug-ref-counting
+     (ref-count :allocation :alien :type int :reader ref-count))
     (:metaclass gobject-class)
-    (:alien-name "GObject")))
-
-(defmethod initialize-instance ((object gobject) &rest initargs)
-  ;; Extract initargs which we should pass directly to the GObeject
-  ;; constructor
-  (let* ((slotds (class-slots (class-of object)))
-	 (args (when initargs
-		 (loop 
-		  as (key value . rest) = initargs then rest
-		  as slotd = (find-if
-			      #'(lambda (slotd)
-				  (member key (slot-definition-initargs slotd)))
-			      slotds)
-		  when (and (typep slotd 'effective-property-slot-definition)
-			    (slot-value slotd 'construct))
-		  collect (progn 
-			    (remf initargs key)
-			    (list 
-			     (slot-definition-pname slotd)
-			     (slot-definition-type slotd)
-			     value))
-		  while rest))))
-    (if args
-	(let* ((string-size (size-of 'string))
-	       (string-writer (writer-function 'string))
-	       (string-destroy (destroy-function 'string))
-	       (params (allocate-memory 
-			(* (length args) (+ string-size +gvalue-size+)))))
-	  (loop
-	   for (pname type value) in args
-	   as tmp = params then (sap+ tmp (+ string-size +gvalue-size+))
-	   do (funcall string-writer pname tmp)
-	   (gvalue-init (sap+ tmp string-size) type value))
+    (:gtype "GObject")))
+
+#+debug-ref-counting
+(defmethod print-object ((instance gobject) stream)
+  (print-unreadable-object (instance stream :type t :identity nil)
+    (if (proxy-valid-p instance)
+	(format stream "at 0x~X (~D)" (sap-int (foreign-location instance)) (ref-count instance))
+      (write-string "at \"unbound\"" stream))))
+
+
+(defun initial-add (object function initargs key pkey)
+  (loop 
+   as (initarg value . rest) = initargs then rest
+   do (cond
+       ((eq initarg key) (funcall function object value))
+       ((eq initarg pkey) (mapc #'(lambda (value)
+				    (funcall function object value))
+				value)))
+       while rest))
+
+(defun initial-apply-add (object function initargs key pkey)
+  (initial-add object #'(lambda (object value)
+			  (apply function object (mklist value)))
+	       initargs key pkey))
+
+
+(defmethod make-proxy-instance ((class gobject-class) location &rest initargs)
+  (declare (ignore location initargs))
+  (if (slot-value class 'instance-slots-p)
+      (error "An object of class ~A has instance slots and should only be created with MAKE-INSTANCE" class)
+    (call-next-method)))
+
+
+(defmethod allocate-foreign ((object gobject) &rest initargs)
+  (let ((init-slots ())) 
+    (flet ((value-from-initargs (slotd)
+	     (loop
+	      with slot-initargs = (slot-definition-initargs slotd)
+	      for (initarg value) on initargs by #'cddr
+	      when (find initarg slot-initargs)
+	      do (return (values value t)))))
+
+    (loop 
+     for slotd in (class-slots (class-of object))
+     when (and 
+	   (eq (slot-definition-allocation slotd) :property)
+	   (construct-only-property-p slotd))
+     do (multiple-value-bind (value initarg-p) (value-from-initargs slotd)
+	  (cond
+	   (initarg-p (push (cons slotd value) init-slots))
+	   ((slot-definition-initfunction slotd)
+	    (push 
+	     (cons slotd (funcall (slot-definition-initfunction slotd)))
+	     init-slots))))))
+
+    (cond
+     (init-slots
+      (let ((element-size (+ +gvalue-size+ +size-of-pointer+))
+	    (num-slots (length init-slots)))
+	(with-allocated-memory (params (* num-slots element-size))
+          (loop
+	   with string-writer = (writer-function 'string)
+	   for (slotd . value) in init-slots
+	   as offset = params then (sap+ offset element-size)
+	   as type = (slot-definition-type slotd)
+	   as pname = (slot-definition-pname slotd)
+	   do (funcall string-writer pname offset)
+              (gvalue-init (sap+ offset +size-of-pointer+) type value))
+
 	  (unwind-protect
-	       (setf  
-		(slot-value object 'location) 
-		(%gobject-newv (type-number-of object) (length args) params))
+	      (%gobject-newv (type-number-of object) num-slots params)
+	
 	    (loop
-	     repeat (length args)
-	     as tmp = params then (sap+ tmp (+ string-size +gvalue-size+))
-	     do (funcall string-destroy tmp)
-	     (gvalue-unset (sap+ tmp string-size)))
-	    (deallocate-memory params)))
-	(setf  
-	 (slot-value object 'location) 
-	 (%gobject-new (type-number-of object)))))
+	     with string-destroy = (destroy-function 'string)
+	     repeat num-slots
+	     as offset = params then (sap+ offset element-size)
+	     do (funcall string-destroy offset)
+	        (gvalue-unset (sap+ offset +size-of-pointer+)))))))
+
+     (t (%gobject-new (type-number-of object))))))
+
+
+(defmethod shared-initialize ((object gobject) names &rest initargs)
+  (declare (ignore names initargs))
+  (let ((*ignore-setting-construct-only-property* t))
+    (call-next-method)))
 
-  (apply #'call-next-method object initargs))
+(defmethod initialize-instance :around ((object gobject) &rest initargs)
+  (declare (ignore initargs))
+  (prog1
+      (call-next-method)
+    #+debug-ref-counting(%object-weak-ref (foreign-location object))
+    #+glib2.8
+    (when (slot-value (class-of object) 'instance-slots-p)
+      (with-slots (location) object
+        (%object-add-toggle-ref location)
+	(%object-unref location)))))
 
 
 (defmethod instance-finalizer ((instance gobject))
-  (let ((location (proxy-location instance)))
+  (let ((location (foreign-location instance)))
+    #+glib2.8
+    (if (slot-value (class-of instance) 'instance-slots-p)
+	#'(lambda ()
+	    #+debug-ref-counting
+	    (format t "Finalizing proxy for 0x~8,'0X~%" (sap-int location))
+	    (remove-cached-instance location)
+	    (%object-remove-toggle-ref location))
+      #'(lambda ()
+	  #+debug-ref-counting
+	  (format t "Finalizing proxy for 0x~8,'0X~%" (sap-int location))
+	  (remove-cached-instance location)
+	  (%object-unref location)))
+    #-glib2.8
     #'(lambda ()
 	(remove-cached-instance location)
-	(%object-unref location))))
+	  (%object-unref location))))
 
 
 (defbinding (%gobject-new "g_object_new") () pointer
@@ -232,28 +375,49 @@ (defbinding object-freeze-notify () nil
 (defbinding object-thaw-notify () nil
   (object gobject))
 
+
+;;;; User data
+
 (defbinding %object-set-qdata-full () nil
   (object gobject)
   (id quark)
   (data unsigned-long)
-  (destroy-marshal pointer))
+  (destroy-marshal callback))
 
+(define-callback user-data-destroy-callback nil ((id unsigned-int))
+  (destroy-user-data id))
 
-;;;; User data
+(defun (setf user-data) (data object key)
+  (%object-set-qdata-full object (quark-intern key)
+   (register-user-data data) user-data-destroy-callback)
+  data)
 
+;; deprecated
 (defun (setf object-data) (data object key &key (test #'eq))
-  (%object-set-qdata-full
-   object (quark-from-object key :test test)
-   (register-user-data data) (callback %destroy-user-data))
-  data)
+  (assert (eq test #'eq))
+  (setf (user-data object key) data))
 
 (defbinding %object-get-qdata () unsigned-long
   (object gobject)		 
   (id quark))
 
+(defun user-data (object key)
+  (find-user-data (%object-get-qdata object (quark-intern key))))
+
+;; deprecated
 (defun object-data (object key &key (test #'eq))
-  (find-user-data
-   (%object-get-qdata object (quark-from-object key :test test))))
+  (assert (eq test #'eq))
+  (user-data object key))
+
+(defun user-data-p (object key)
+  (user-data-exists-p (%object-get-qdata object (quark-intern key))))
+
+(defbinding %object-steal-qdata () unsigned-long
+  (object gobject)		 
+  (id quark))
+
+(defun unset-user-data (object key)
+  (destroy-user-data (%object-steal-qdata object (quark-intern key))))
 
 
 ;;;;
@@ -275,14 +439,15 @@ (defun %map-params (params length type inherited-p)
       (nreverse properties))))
 
 (defun query-object-class-properties (type &optional inherited-p)
-  (let* ((type-number (find-type-number type))
+  (let* ((type-number (find-type-number type t))
 	 (class (type-class-ref type-number)))
     (unwind-protect
 	 (multiple-value-bind (array length)
 	     (%object-class-list-properties class)
-	   (unwind-protect
-		(%map-params array length type-number inherited-p)
-	     (deallocate-memory array)))
+	   (unless (null-pointer-p array)
+	     (unwind-protect
+		 (%map-params array length type-number inherited-p)
+	       (deallocate-memory array))))
 ;      (type-class-unref type-number)
       )))
 
@@ -297,14 +462,18 @@ (defun default-slot-accessor (class-name slot-name type)
     (if (eq type 'boolean) "-P" ""))))
 
 
-(defun slot-definition-from-property (class property)
+(defun slot-definition-from-property (class property &optional slot-name args)
   (with-slots (name flags value-type documentation) property
-    (let* ((slot-name (default-slot-name name))
-	   (slot-type (or (type-from-number value-type) value-type))
+    (let* ((slot-name (or slot-name (default-slot-name name)))
+	   (slot-type (or (getf args :type) (type-from-number value-type) 'pointer))
 	   (accessor (default-slot-accessor class slot-name slot-type)))
       
       `(,slot-name
 	:allocation :property :pname ,name
+
+	,@(when (find :unbound args) (list :unbound (getf args :unbound)))
+	,@(when (find :getter args) (list :getter (getf args :getter)))
+	,@(when (find :setter args) (list :setter (getf args :setter)))
 	
 	;; accessors
 	,@(cond
@@ -323,15 +492,19 @@ (defun slot-definition-from-property (class property)
 	    '(:writable nil))
 	,@(when (not (member :readable flags))
 	    '(:readable nil))
-	,@(when (or (member :construct flags) 
-		    (member :construct-only flags))
-	    '(:construct t))
+	,@(when (member :construct-only flags)
+	    '(:construct-only t))
 	
 	;; initargs
-	,@(when (or (member :construct flags)
-		    (member :construct-only flags)
-		    (member :writable flags))
-	    (list :initarg (intern (string slot-name) "KEYWORD")))
+	,@(if (find :initarg args)
+	      (let ((initarg (getf args :initarg)))
+		(etypecase initarg
+		  (null ())
+		  (symbol `(:initarg ,initarg))))
+	    (when (or (member :construct flags)
+		      (member :construct-only flags)
+		      (member :writable flags))
+	      (list :initarg (intern (string slot-name) "KEYWORD"))))
 	
 	:type ,slot-type
 	:documentation ,documentation))))
@@ -339,27 +512,61 @@ (defun slot-definition-from-property (class property)
 
 (defun slot-definitions (class properties slots)
   (loop 
-   with manual-slots = slots
    for property in properties
-   unless (find-if 
-	   #'(lambda (slot)
-	       (destructuring-bind (name &rest args) slot
-		 (or 
-		  (equal (param-name property) (getf args :pname))
-		  (eq (default-slot-name (param-name property)) name))))
-	   manual-slots)
-   do (push (slot-definition-from-property class property) slots))
+   as slot = (or
+	      (find (param-name property) slots 
+	       :key #'(lambda (slot) (getf (rest slot) :pname)) 
+	       :test #'string=)
+	      (find (param-name property) slots 
+	       :key #'first :test #'string-equal))
+   do (cond
+       ((not slot) 
+	(push (slot-definition-from-property class property) slots))
+       ((getf (rest slot) :merge)
+	(setf 
+	 (rest slot) 
+	 (rest (slot-definition-from-property class property (first slot) (rest slot)))))))
   (delete-if #'(lambda (slot) (getf (rest slot) :ignore)) slots))
 
 
-(defun expand-gobject-type (type &optional options (metaclass 'gobject-class))
+(defun expand-gobject-type (type forward-p options &optional (metaclass 'gobject-class))
   (let ((supers (cons (supertype type) (implements type)))
 	(class  (type-from-number type))
 	(slots (getf options :slots)))    
     `(defclass ,class ,supers
-      ,(slot-definitions class (query-object-class-properties type) slots)
-      (:metaclass ,metaclass)
-      (:alien-name ,(find-type-name type)))))
-
-
-(register-derivable-type 'gobject "GObject" 'expand-gobject-type)
+	 ,(unless forward-p
+	    (slot-definitions class (query-object-class-properties type) slots))
+	 (:metaclass ,metaclass)
+	 (:gtype ,(register-type-as type)))))
+
+(defun gobject-dependencies (type)
+  (delete-duplicates 
+   (cons
+    (supertype type)
+    (append 
+     (type-interfaces type)
+     (mapcar #'param-value-type (query-object-class-properties type))))))
+
+
+(register-derivable-type 'gobject "GObject" 'expand-gobject-type 'gobject-dependencies)
+
+
+;;; Pseudo type for gobject instances which have their reference count
+;;; increased by the returning function
+
+(defmethod alien-type ((type (eql 'referenced)) &rest args)
+  (declare (ignore type args))
+  (alien-type 'gobject))
+
+(defmethod from-alien-form (form (type (eql 'referenced)) &rest args)
+  (declare (ignore type))
+  (destructuring-bind (type) args
+    (if (subtypep type 'gobject)
+	(let ((instance (make-symbol "INSTANCE")))
+	  `(let ((,instance ,(from-alien-form form type)))
+	     (when ,instance
+	       (%object-unref (foreign-location ,instance)))
+	     ,instance))
+      (error "~A is not a subclass of GOBJECT" type))))
+
+(export 'referenced)