flex Expert System Toolkit - LPIS

9. Flex Predicates 141
flex toolkit
new_default( colour, albino, white ).
new_demon( +Name,?Attribute,?Frame,?Old,?New,+Context,+Action )
Create (or update if the Name already exists) a demon which reacts to slot
updates (see new_slot/3).
The Action (a Prolog call) is initiated whenever the Attribute of the
Frame changes from some Old value (the atom unknown if there is no
current value) to some New value.
In addition, the Context (a Prolog call) must also hold before the demon
can be activated.
The Action (a Prolog call) occurs immediately after the update, and will
therefore not affect the update itself.
Examples
new_demon(spying_slots, Attribute, Frame,
Old, New, true,
( write(Attribute(Frame) = (Old-->New)), nl )
)
new_demon( check_meltdown, global, temperature, _, T,
comparison(>,T,boiling_point),
( remember_fact(danger_level(red)), shut_down
) )
new_frame( +Name,+Parents )
A new frame called Name is created whose position in the frame hierarchy is
determined by its list of Parents. These Parents determine from where
values can be inherited.
Examples
new_frame( animal, [] ) .
new_frame( mammal, [animal] ) .
new_frame( whale, [mammal,ocean_dweller] ) .
new_function( +Name, +Arguments, +Value )
Record the definition of a function Name. Functions are evaluated at runtime
through calls to dereference/2.
Example
new_function( father, [X], (Y : (parent(X,Y),male(Y)))
) .