Vala + GTK "Hello World"

Kenny_Strawn · 10-15-2010, 10:53 PM

Is there any documentation on how to create this in Vala? I am clueless, as there is a HUGE lack of documentation on Vala in general, and even the little documentation there is is only partially written, except for this.

I decided to stick to Vala as my beginner's programming language to study, as it includes the necessary content I need (object-oriented, GNOME/GTK friendly) and I am studying it all I can. I am not posting any code right now; I plan to take other members' advice here and slowly write/test code before it goes into a new project.

Again: Any help is appreciated in creating a "Hello World" GTK window using Vala.

Sergei Steshenko · 10-16-2010, 02:21 AM

Right choice ! (Because I know nothing about Vala).

MTK358 · 10-16-2010, 07:39 AM

I'm not trying to push you, but you can also check out Python (a relatively beginner-friendly language). They have GTK+ bindings for it (and Qt bindings, too).

Sergei Steshenko · 10-16-2010, 07:50 AM

Quote:

Originally Posted by MTK358

I'm not trying to push you, but you can also check out Python (a relatively beginner-friendly language). They have GTK+ bindings for it (and Qt bindings, too).

Python (as well as Perl in this case) are wrong choices - because too many forum participants know them.

MTK358 · 10-16-2010, 07:53 AM

I don't get your point.

And anyway, I was just making a suggestion, the OP may check it out if he wants to and might like it, or not.

Sergei Steshenko · 10-16-2010, 07:55 AM

Quote:

Originally Posted by MTK358

I don't get your point.

RockDoctor · 10-16-2010, 08:03 AM

Instead of python, you should have suggested genie. Compiles like vala, even uses the vala precompiler (or whatever it's called), but looks more like python and is even less well-documented than vala.

graemef · 10-16-2010, 11:17 AM

I know nothing about Vala but after a quick search I wondered if you had tried this

MTK358 · 10-16-2010, 11:45 AM

Quote:

Originally Posted by RockDoctor

Instead of python, you should have suggested genie. Compiles like vala, even uses the vala precompiler (or whatever it's called), but looks more like python and is even less well-documented than vala.

I don't know Vala and never heard of Genie. Mostly because I'm more interested in Qt.

Kenny_Strawn · 10-16-2010, 12:54 PM

Got everything right here:

Code:

using GLib;
using Gtk;

public class HelloWorld : Object {
    public static int main(string[] args) {
        Gtk.init(ref args);
		
        var window = new Window(WindowType.TOPLEVEL);
        var label = new Label("Hello World");
		
        window.title = "Hello World";
        window.set_default_size(640, 480);
        window.position = WindowPosition.CENTER;
        window.destroy.connect(Gtk.main_quit);
		
        window.add(label);
        window.show_all();
		
        Gtk.main();
        return 0;
    }
}

Except for one problem:

Code:

HelloWorldGtk.vala:2.7-2.9: error: The namespace name `Gtk' could not be found

Is there some library I have to install? I already have libgtk3.0-dev installed.

MTK358 · 10-16-2010, 01:23 PM

I looked at the Vala tutorial, and it said:

Code:

public class ClassName : GLib.Object

Sergei Steshenko · 10-16-2010, 01:24 PM

Quote:

Originally Posted by Kenny_Strawn

Got everything right here:

Code:

using GLib;
using Gtk;

public class HelloWorld : Object {
    public static int main(string[] args) {
        Gtk.init(ref args);
		
        var window = new Window(WindowType.TOPLEVEL);
        var label = new Label("Hello World");
		
        window.title = "Hello World";
        window.set_default_size(640, 480);
        window.position = WindowPosition.CENTER;
        window.destroy.connect(Gtk.main_quit);
		
        window.add(label);
        window.show_all();
		
        Gtk.main();
        return 0;
    }
}

Except for one problem:

Code:

HelloWorldGtk.vala:2.7-2.9: error: The namespace name `Gtk' could not be found

Is there some library I have to install? I already have libgtk3.0-dev installed.

I don't think Vala knows about gtk3.

Kenny_Strawn · 10-16-2010, 01:59 PM

Yeah, I kind of figured that Vala didn't know about GTK3 (yet), however, I do know that some programs (e.g. Mutter) that are part of the GNOME Shell JHBuild moduleset actually depend on Vala and have components written in Vala.

And also: If you type:

Code:

using GLib;

at the beginning of the program, you can just type "Object" since the compiler already knows that it's under GLib if you use GLib.

Kenny_Strawn · 10-16-2010, 02:34 PM

I think I've found out the problem:

Code:

valac --pkg gtk+-3.0 HelloWorldGtk.vala

Apparently, I have to invoke this boldfaced argument to the compiler manually.

Kenny_Strawn · 10-16-2010, 03:08 PM

Okay, I also have libgtk2.0-dev installed, so I used it instead. I also found conflicting objects, (GLib.Object and Gtk.Object), so I had to specify "GLib.Object". After that, it compiled successfully. The one thing I like about Vala's error messages is that they're easy for newbies to understand, unlike GCC's. At least so far.

Of course, that doesn't mean I might run into some that aren't so.