The AddInterface method adds an existing interface to the collection of interfaces that are implemented by a particular class.
Call object.AddInterface(interfaceDef, flag)
The AddInterface method syntax has the following parts.
| Part | Description |
| object | An object expression that evaluates to a ClassDef object. |
| interfaceDef | The InterfaceDef definition object for the interface that is to be added to the collection of interfaces that are implemented by this class. |
| flag | If the interface that you are adding is the default interface for the class, pass in the string "Default". Otherwise, pass in a null string. |
When you indicate that an interface is the default interface for a class, you are actually setting the value of the ImplementsOptions annotational property on the Class_Implements_Interface relationship to TRUE. (Remember that every relationship can have annotational properties set on it.)