How to create a thread safe singleton in vala?

Question

I want to create a thread-safe singleton instance for my vala class.

As you know, singletons may lead to threading issues if not properly implemented.

Answer 1

Also you can use SingleInstance Code Attribute. It does the same for you automatically!

[SingleInstance]
public class ExampleClass : Object {
    public int prop { get; set; default = 42; }
    public ExampleClass () {
        // ...
    }
}

int main (string[] args) {
    var a = new ExampleClass (); // the two refs
    var b = new ExampleClass (); // are the same
    b.prop += 1;
    assert (a.prop == b.prop);
    return 0;
}

Note, that in this case you don't need to call a static function like instance() or get_instance(). Simply creating an object via new will give you a reference to the singleton.