class StorableShape : Shape {
	private class MyDBObject : DBObject {
		override void saveState() {
			// access DBObject and StorableShape
			. . .
		}
	}
	private MyDBObject _store;
	alias _store this;
	this( ) {
		// Here’s the crucial point where the link is made
		_store = this. new MyDBObject;
	}
	. . .
}