These procedures are triggered depending on how the attribute is accessed. Like all object-oriented systems, instance frames can inherit properties from generic frames in a hierarchy. In iProlog , frames are stored in Prolog's database and their contents can be queried and matched in the same way as other data. This section describes a front-end to iProlog that provides a convenient syntax for manipulating frames. Slots Generic frames describe generic objects, e.g. person, physical object, etc.
Facets are labels which identify the type of demon.
The allowable facets are described in the Reference Manual. Demons are procedures that are attached to slots and are triggered automatically by different kinds of accesses to the frame. They are written in Prolog. The inheritance specification may be a single name such as object in the example above, or it may be a list. This means that the object would inherit all the properties of cylinder and container .