more Vala examples

vala/hello/memory.vala

@@ -0,0 +1,30 @@
+class Node : Object {
+    public Node prev;
+    public weak Node next;
+
+    public Node (Node? prev = null) {
+        this.prev = prev;      // ref
+        if (prev != null) {
+            prev.next = this;  // ref
+        }
+    }
+}
+
+/*
+void main () {
+    var n1 = new Node ();    // ref
+    var n2 = new Node (n1);  // ref
+
+    // print the reference count of both objects
+    stdout.printf ("%u, %u\n", n1.ref_count, n2.ref_count);
+
+}   // unref, unref
+*/
+
+void main () {
+    while (true) {
+        var n1 = new Node ();
+        var n2 = new Node (n1);
+        Thread.usleep (100);
+    }
+}