Object.new (type) doesn't work while create_default_instance () does.

vala/abstract_class/gee_abstract.vala

@@ -0,0 +1,74 @@
+public interface IDoc : Object {
+
+	public abstract string generate ();
+	public abstract Object copy ();
+}
+
+public abstract class AbstractDocList : Gee.ArrayList<IDoc>, IDoc {
+
+	protected abstract AbstractDocList create_default_instance ();
+
+	protected AbstractDocList list_copy () {
+		stdout.printf ("AbstractDocList::list_copy ()\n");
+		stdout.printf ("this.get_type ().name () = %s\n", this.get_type ().name ());
+		//var clone = Object.new (this.get_type ()) as AbstractDocList;
+		var clone = create_default_instance ();
+
+		foreach (IDoc dociface in this)
+			clone.add (dociface.copy () as IDoc);
+
+		return clone;
+	}
+
+	public Object copy () {
+		stdout.printf ("AbstractDocList::copy ()\n");
+		return list_copy ();
+	}
+
+	public string generate () {
+		stdout.printf ("AbstractDocList::generate ()\n");
+		var result = new StringBuilder ();
+
+		foreach (IDoc dociface in this)
+			result.append (dociface.generate ());
+
+		return result.str;
+	}
+}
+
+public class Text : Object, IDoc {
+
+	public string text = "";
+
+	public Text (string text) {
+		this.text = text;
+	}
+
+	public Object copy () {
+		stdout.printf ("Text::copy ()\n");
+		return new Text (text);
+	}
+
+	public string generate () {
+		stdout.printf ("Text::generate ()\n");
+		return text;
+	}
+}
+
+public class Glob : AbstractDocList {
+	protected override AbstractDocList create_default_instance () { return new Glob (); }
+}
+
+IDoc CreateObject () {
+	var glob = new Glob ();
+	for (var i = 0; i < 5; ++i) {
+		glob.add (new Text (i.to_string ()));
+	}
+	return glob;
+}
+
+void main () {
+	//stdout.printf ("Hello world!\n");
+	var idoc = CreateObject ();
+	stdout.printf ("idoc.generate () = %s\n", (idoc.copy () as IDoc).generate ());
+}