Unique Features of Frames
Frame systems typically have the following
features in contrast to typical object-oriented systems:
- Richer slots. A slot can contain more kinds of information, e.g.,
documentation, default value, restrictions on slot fillers,
if-added and if-removed methods.
- Slot orientation. There usually are no ``messages'' that are not
associated with slots.
- More complex structure. A frame system could potentially have
instance values, default values, and if-needed methods for the same
slot. When all these are combined with multiple inheritance paths,
the result can be complex.