For any existing class in your project, you can change the metaclass you use for that class. This gives the class and the Class Form the attributes defined by the new metaclasses. New classes that you create as subclasses of the class will also use the new metaclass. However, existing subclasses will continue to use their previously assigned metaclass unless you specifically change it.
This example uses the newspaper_extended project, which includes the diagram project and tables project, both of which supply metaclass structure. You can also use these structures in your own projects by including the corresponding project. However, you must structure your project in a specific way in order to be able to use these features. See the tutorial for more information.
To change the metaclass of an existing class: