How do I inherit a class?

[ravener]

How does inheritance work? Specifically calling the parent's constructor.

I want to subclass Adw.ApplicationWindow for example, since this wants the application instance in its constructor how would I pass it, I was not able to use the base() properly, and I can't use .New() when subclassing it.

Goal is something like this

class MyWindow : Adw.ApplicationWindow
{
    public MyWindow(Gtk.Application app) : base(app)
    {
        // Do stuff
    }
}

[ravener]

Well some progress, I did this

class MyWindow : Adw.ApplicationWindow
{
    public MyWindow(Gtk.Application app) : base(app.Handle, false)
    {
        // Do stuff
    }
}

That fixed the constructor idea, but now when I new MyWindow(app) and window.Present() it crashes with

Gtk-CRITICAL **: 20:38:56.207: gtk_window_present_with_time: assertion 'GTK_IS_WINDOW (window)' failed

[ravener]

okay after looking closer at how Adw.Application.New works I realized this is the correct way:

class MyWindow : Adw.ApplicationWindow
{
    public MyWindow(Gtk.Application app) : base(New(app).Handle, false)
    {
        // Do stuff
    }
}

This works, though I'm unsure if that's the best practice, how are others dealing with it?

[ravener]

Seems like the alternative is to not initialize the constructor but then later when presenting the window use application.AddWindow

According to Gtk docs this is equivalent to setting the application property of the window so that works and looks better.

[badcel]

To create a proper subclass which is known to the GObject typesystem you would need to call into this constructor

In your case this would be this constructor.

In general I would advice against subclasses as GTK itself is trying to avoid it. In general for a C# programmer I would only recommend subclasses if there are specific arguments for it (similar to GTK) as inheritance chains are not very flexible and tend to lead to complex / harder to maintain code.

[ravener]

Yeah, I don't like dealing with GObject types, it's just a common pattern to separate the main window to a class extending Adw.ApplicationWindow, I've seen it done everywhere from Vala to Rust, so at least for that class.