AXAPTA - Call a class extended from another with name string

There are three ways:

1- classFactory.createClass(className2Id('MyClass'))

2- test1  test;
    DictClass d;

    d = new DictClass(className2Id("test1"));
    test = d.makeObject(222);
    test.MyTest();
3. Just for AX 2012 için extension framework . I'll look up this later.