On 9/8/05, Murray Cumming <[EMAIL PROTECTED]> wrote:
> On Tue, 2005-09-06 at 08:26 -0500, Jonathon Jongsma wrote:
> > I'm curious, is it legal to emit a signal within a handler for another
> > signal?
>
> Yes, absolutely.
>
> > The reason I'm asking is that I'm trying to do such a thing
> > and I keep getting a segfault when the event occurs.
>
> gdb or valgrind will give more information.
>
Here's the backtrace from gdb. item #2 is obviously my handler for a
button_release_event, which then emits my custom signal. I'm afraid
that I can't figure a lot out from this backtrace -- do you see
anything obvious here? (code is shown below)
Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 16384 (LWP 12572)]
0x40ccd37e in std::_List_node_base::swap () from /usr/lib/libstdc++.so.6
(gdb) bt
#0 0x40ccd37e in std::_List_node_base::swap () from /usr/lib/libstdc++.so.6
#1 0x0807dabe in sigc::internal::signal_emit0<bool, sigc::nil>::emit (
impl=0x817d748) at stl_list.h:901
#2 0x08078c4f in gcs::Widgets::ColorSwatch::on_button_release_event (
this=0x19, e=0x8254d20) at signal.h:1608
#3 0x4021d6c2 in Gtk::Widget_Class::button_release_event_callback ()
from /usr/lib/libgtkmm-2.4.so.1
#4 0x4078747e in _gtk_marshal_BOOLEAN__BOXED ()
from /usr/lib/libgtk-x11-2.0.so.0
#5 0x40a71f18 in g_cclosure_new_swap () from /usr/lib/libgobject-2.0.so.0
#6 0x40a725bb in g_closure_invoke () from /usr/lib/libgobject-2.0.so.0
#7 0x40a81c72 in g_signal_stop_emission () from /usr/lib/libgobject-2.0.so.0
#8 0x40a82c05 in g_signal_emit_valist () from /usr/lib/libgobject-2.0.so.0
#9 0x40a831fe in g_signal_emit () from /usr/lib/libgobject-2.0.so.0
#10 0x40876cf7 in gtk_widget_send_expose () from /usr/lib/libgtk-x11-2.0.so.0
#11 0x40785f92 in gtk_propagate_event () from /usr/lib/libgtk-x11-2.0.so.0
#12 0x40784de6 in gtk_main_do_event () from /usr/lib/libgtk-x11-2.0.so.0
#13 0x409868e5 in _gdk_events_queue () from /usr/lib/libgdk-x11-2.0.so.0
#14 0x40c243f1 in g_main_context_dispatch () from /usr/lib/libglib-2.0.so.0
#15 0x40c27647 in g_main_context_check () from /usr/lib/libglib-2.0.so.0
#16 0x40c27b98 in g_main_loop_run () from /usr/lib/libglib-2.0.so.0
#17 0x40784693 in gtk_main () from /usr/lib/libgtk-x11-2.0.so.0
#18 0x401b3359 in Gtk::Main::run_impl () from /usr/lib/libgtkmm-2.4.so.1
#19 0x401b31a3 in Gtk::Main::run () from /usr/lib/libgtkmm-2.4.so.1
#20 0x0806de26 in main (argc=1, argv=0xbffff644) at main.cc:73
Here's my on_button_release_event code:
bool ColorSwatch::on_button_release_event(GdkEventButton *e)
{
//if (e->type == GDK_BUTTON_RELEASE)
{
if (e->button == 1)
{
// User pressed left mouse button
m_signal_selected.emit();
debug("In on_button_press_event; emitted signal_selected()");
}
}
return true;
}
m_signal_selected is defined as follows:
sigc::signal<bool> m_signal_selected;
I've registered a handler for m_signal_selected in the constructor of
the class as follows:
m_signal_selected.connect(sigc::mem_fun(*this, &ColorSwatch::on_test));
The handler on_test is defined as follows:
bool ColorSwatch::on_test()
{
debug("on_test");
return true;
}
When I register even a trivial handler for m_signal_selected (such as
on_test shown above), I get a segmentation fault (backtrace shown
above). When I have no signal handler registered for
m_signal_selected, the signal emits but no segfault occurs.
I'd be grateful for any help anyone can provide.
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