Re: patch for g_nullify_pointer() and friends

[Sven Neumann <sven gimp org>]

Hi,

here's a new patch. I stayed with g_nullify_pointer() since I agree
with Tim on this subject. The GObject additions are implemented as
functions now and are documented inline. Someone should please check 
that I found the correct words. The patch also adds a simple test
case to testgruntime. There should probably be more tests there...


Salut, Sven

Index: glib/gutils.c
===================================================================
RCS file: /cvs/gnome/glib/glib/gutils.c,v
retrieving revision 1.97
diff -u -r1.97 gutils.c
--- glib/gutils.c	2001/06/30 16:54:32	1.97
+++ glib/gutils.c	2001/08/06 18:42:05
@@ -1046,6 +1046,20 @@
 }
 
 /**
+ * g_nullify_pointer:
+ * @nullify_location: the memory address of the pointer.
+ * 
+ * Set the pointer at the specified location to %NULL.
+ **/
+void
+g_nullify_pointer (gpointer *nullify_location)
+{
+  g_return_if_fail (nullify_location != NULL);
+
+  *nullify_location = NULL;
+}
+
+/**
  * g_get_codeset:
  * 
  * Get the codeset for the current locale.
Index: glib/gutils.h
===================================================================
RCS file: /cvs/gnome/glib/glib/gutils.h,v
retrieving revision 1.10
diff -u -r1.10 gutils.h
--- glib/gutils.h	2001/07/10 22:37:07	1.10
+++ glib/gutils.h	2001/08/06 18:42:05
@@ -165,6 +165,10 @@
 gchar*                g_path_get_basename  (const gchar *file_name);
 gchar*                g_path_get_dirname   (const gchar *file_name);
 
+
+/* Set the pointer at the specified location to NULL */
+void                  g_nullify_pointer    (gpointer    *nullify_location);
+
 /* Get the codeset for the current locale */
 /* gchar * g_get_codeset    (void); */
 
Index: gobject/gobject.c
===================================================================
RCS file: /cvs/gnome/glib/gobject/gobject.c,v
retrieving revision 1.39
diff -u -r1.39 gobject.c
--- gobject/gobject.c	2001/07/02 05:15:29	1.39
+++ gobject/gobject.c	2001/08/06 18:42:05
@@ -1262,6 +1262,49 @@
     g_warning (G_STRLOC ": couldn't find weak ref %p(%p)", notify, data);
 }
 
+/**
+ * g_object_add_weak_pointer:
+ * @object: the object that should be weak referenced.
+ * @weak_pointer_location: the memory address of a pointer.
+ * 
+ * Adds a weak reference from weak_pointer to @object to indicate that
+ * the pointer located at @weak_pointer_location is only valid during the 
+ * lifetime of @object. When the @object is finalized, @weak_pointer will 
+ * be set to %NULL.
+ **/
+void
+g_object_add_weak_pointer (GObject  *object, 
+                           gpointer *weak_pointer_location)
+{
+  g_return_if_fail (G_IS_OBJECT (object));
+  g_return_if_fail (weak_pointer_location != NULL);
+
+  g_object_weak_ref (object, 
+                     (GWeakNotify) g_nullify_pointer, 
+                     weak_pointer_location);
+}
+
+/**
+ * g_object_remove_weak_pointer:
+ * @object: the object that is weak referenced.
+ * @weak_pointer_location: the memory address of a pointer.
+ *
+ * Removes a weak reference from @object that was previously added
+ * using g_object_add_weak_pointer(). The @weak_pointer_location has
+ * to match the one used with g_object_add_weak_pointer().
+ **/
+void
+g_object_remove_weak_pointer (GObject  *object, 
+                              gpointer *weak_pointer_location)
+{
+  g_return_if_fail (G_IS_OBJECT (object));
+  g_return_if_fail (weak_pointer_location != NULL);
+
+  g_object_weak_unref (object, 
+                       (GWeakNotify) g_nullify_pointer, 
+                       weak_pointer_location);
+}
+
 gpointer
 g_object_ref (gpointer _object)
 {
Index: gobject/gobject.h
===================================================================
RCS file: /cvs/gnome/glib/gobject/gobject.h,v
retrieving revision 1.16
diff -u -r1.16 gobject.h
--- gobject/gobject.h	2001/07/02 05:02:13	1.16
+++ gobject/gobject.h	2001/08/06 18:42:05
@@ -154,6 +154,10 @@
 void	    g_object_weak_unref		      (GObject	      *object,
 					       GWeakNotify     notify,
 					       gpointer	       data);
+void        g_object_add_weak_pointer         (GObject        *object, 
+                                               gpointer       *weak_pointer_location);
+void        g_object_remove_weak_pointer      (GObject        *object, 
+                                               gpointer       *weak_pointer_location);
 gpointer    g_object_get_qdata                (GObject        *object,
 					       GQuark          quark);
 void        g_object_set_qdata                (GObject        *object,
Index: gobject/testgruntime.c
===================================================================
RCS file: /cvs/gnome/glib/gobject/testgruntime.c,v
retrieving revision 1.3
diff -u -r1.3 testgruntime.c
--- gobject/testgruntime.c	2001/06/30 17:17:41	1.3
+++ gobject/testgruntime.c	2001/08/06 18:42:05
@@ -161,8 +161,10 @@
 main (int   argc,
       char *argv[])
 {
-  TestObject *tobject, *sigarg;
-  gchar *string = NULL;
+  TestObject *tobject;
+  TestObject *sigarg;
+  gpointer    tobject_address;
+  gchar      *string = NULL;
 
   g_log_set_always_fatal (g_log_set_always_fatal (G_LOG_FATAL_MASK) |
 			  G_LOG_LEVEL_WARNING |
@@ -170,13 +172,21 @@
   g_type_init_with_debug_flags (G_TYPE_DEBUG_OBJECTS | G_TYPE_DEBUG_SIGNALS);
 
   tobject = g_object_new (TEST_TYPE_OBJECT, NULL);
+  tobject_address = tobject;
+  g_object_add_weak_pointer (G_OBJECT (tobject), &tobject_address);
+
   sigarg = g_object_new (TEST_TYPE_OBJECT, NULL);
+
   g_signal_emit_by_name (tobject, "test-signal", sigarg, NULL, &string);
   g_message ("signal return: \"%s\"", string);
   g_free (string);
   
   g_object_unref (sigarg);
   g_object_unref (tobject);
+  
+  if (tobject_address != NULL)
+    g_message ("g_object_add_weak_pointer() failed, "
+               "tobject_address should be NULL.");
 
   g_message ("%s done", argv[0]);