Re: [Vala] GTK and Property problems

[pHilipp Zabel <philipp zabel gmail com>]

On Sat, Jun 26, 2010 at 9:36 AM, Andrew <rugby471 gmail com> wrote:
> HI guys,
>
> Perhaps the simplest way to ask this is, could anyone tell me why when
> the attached file (Genie) is compiled and then run, do I get these error
> messages?
>
> (wasiliana:2710): Gtk-CRITICAL **: gtk_container_add: assertion
> `GTK_IS_CONTAINER (container)' failed
> (wasiliana:2710): GLib-GObject-WARNING **: invalid (NULL) pointer instance
> (wasiliana:2710): GLib-GObject-CRITICAL **: g_signal_connect_object:
> assertion `G_TYPE_CHECK_INSTANCE (instance)' failed

I accidentally replied off-list, saying this is because the widgets
are created as local variables which are never assigned to the object
properties.
My first idea to fix this was just to assign to the properties directly:

--- main.gs.orig        2010-06-26 12:04:28.061569285 +0200
+++ main.gs     2010-06-26 12:18:32.577892738 +0200
@@ -47,13 +47,13 @@
        this.delete_event.connect(on_mainwindow_delete_event)

        // Toolbar creation
-        var scrolled_window = new ScrolledWindow(null, null)
+        scrolled_window = new ScrolledWindow(null, null)
        var vbox = new VBox(false, 0)
        var toolbar_hbox = new HBox(true, 0)
-        var toolbar = new Toolbar()
+        toolbar = new Toolbar()
        var back_button = new ToolButton.from_stock("gtk-go-back")
-        var forward_button = new ToolButton.from_stock("gtk-go-forward")
-        var location_entry = new Entry()
+        forward_button = new ToolButton.from_stock("gtk-go-forward")
+        location_entry = new Entry()

        //Toolbar Packing
        toolbar.insert(back_button, -1)

But that failed (after compilation with valac 0.8.0), because the
property assignment didn't increase the refcount on the widgets.
Is this a bug in the Genie code generator? Is it fixed in current versions?
For comparison, this is the C output for the scrolled_window setter method:

void main_window_set_scrolled_window (MainWindow* self,
GtkScrolledWindow* value) {
       g_return_if_fail (self != NULL);
       self->priv->_scrolled_window = value;
       g_object_notify ((GObject *) self, "scrolled-window");
}

And this is what I would have expected instead (and what I get from
vala 0.8.0 when compiling from a .vala source instead of from .gs
source):

void main_window_set_scrolled_window (MainWindow* self,
GtkScrolledWindow* value) {
       GtkScrolledWindow* _tmp0_;
       g_return_if_fail (self != NULL);
       self->priv->_scrolled_window = (_tmp0_ = _g_object_ref0 (value),
_g_object_unref0 (self->priv->_scrolled_window), _tmp0_);
       g_object_notify ((GObject *) self, "scrolled-window");
}

regards
Philipp