Re: Crashes using custom signals

[dexter <dexter balabit hu>]

Hi,

I'm not sure, but I think you're missing the Gtk::Main initialization 
before creating the mainwindow. So this:
> Application::Application()
>     : _main_window(new MainWindow)
> {

should be something like this:
> Application::Application(int &argc, char **&argv)
>     : Gtk::Main(argc, argv), _main_window(new MainWindow)
> {


> ----- Original Message -----
> From: "Phillip Neiswanger" <sigsegv0 gmail com>
> To: gtkmm-list gnome org
> Sent: Thu, Jan 15, 2009 3:02:13 AM +0100
> Subject: Crashes using custom signals
>
> Hi,
>
> At this end of this message is a simple test program. Note the connect() 
> call in the Application constructor. If I move the connect() out of that 
> constructor and into the MainWindow constructor like so:
>
> MainWindow::MainWindow()
> {
>     Application::instance()->
>         signal_a().
>            connect(sigc::mem_fun(*this, &MainWindow::on_a));
> }
>
> I get a core dump in the connect() call. The back trace looks like this:
>
> (gdb) bt
> #0  0x48cfb89f in std::_List_node_base::hook () from 
> /usr/lib/libstdc++.so.5
> #1  0x48808501 in std::list<sigc::slot_base, 
> std::allocator<sigc::slot_base> >::insert () from 
> /usr/X11R6/lib/libglibmm-2.4.so.1
> #2  0x488292ff in sigc::internal::signal_impl::insert ()
>    from /usr/X11R6/lib/libsigc-2.0.so.0
> #3  0x48829343 in sigc::internal::signal_impl::connect ()
>    from /usr/X11R6/lib/libsigc-2.0.so.0
> #4  0x48829526 in sigc::signal_base::connect ()
>    from /usr/X11R6/lib/libsigc-2.0.so.0
> #5  0x0804ce7c in sigc::signal0<void, sigc::nil>::connect (this=0xbfbfe7c0,
>     slot_= 0xbfbfe7e0) at signal.h:2655
> #6  0x0804c3fe in MainWindow (this=0x8092180) at t.cc:39
> #7  0x0804c96c in Application (this=0xbfbfe860) at t.cc:54
> #8  0x0804cc91 in main () at t.cc:82
>
> Why? What's wrong with my code?
>
> Here's the code:
>
> #include <gtkmm/main.h>
> #include <gtkmm/window.h>
>
> #include <memory>
> #include <iostream>
>
> typedef sigc::signal<void> SignalTypeA;
>
> class MainWindow;
>
> class Application : public Gtk::Main
> {
>   public:
>     Application();
>    ~Application();
>
>     SignalTypeA signal_a();
>
>     static Application* instance();
>
>     void run();
>
>   private:
>     std::auto_ptr<MainWindow> _main_window;
>     SignalTypeA _signal_a;
> };
>
> class MainWindow : public Gtk::Window
> {
>   public:
>     MainWindow();
>    ~MainWindow();
>
>     void on_a();
> };
>
> MainWindow::MainWindow()
> {
> }
>
> MainWindow::~MainWindow()
> {
> }
>
> void
> MainWindow::on_a()
> {
> std::cout << "Test output" << std::endl;
> }
>
> Application::Application()
>     : _main_window(new MainWindow)
> {
>     signal_a().connect(sigc::mem_fun(*_main_window, &MainWindow::on_a));
> }
>
> Application::~Application()
> {
> }
>
> SignalTypeA
> Application::signal_a()
> {
>     return _signal_a;
> }
>
> Application*
> Application::instance()
> {
>     return dynamic_cast<Application*>(Gtk::Main::instance());
> }
>
> void
> Application::run()
> {
>     Gtk::Main::run(*_main_window);
> }
>
> int
> main()
> {
>     Application app;
>
>     app.run();
>
>     return 0;
> }
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