1. AI/ES (Artificial Intelligence / Expert System) Visual Prolog: Part 4
2012. Fall.
SME., Pukyong Nat’l Univ.
Kim, Minsoo

2. Contents
Classes and Objects
Classes and Modules
Holding Objects

3. Classes and Objects The world of object orientation
The world consists of identifiable objects.
Person, Cat, Dog, …
An object has certain characteristics(attributes).
Person: name, length, weight, iq, …
Objects can do something (tasks).
Operations / methods
Person: run, smile, talk, …
The set of objects with the same operations and attributes  class
Jack, Linda, John, …  Person
Objects are related to each other.

4. Classes and Objects Class vs. Object Class: User-Defined Type(Domain)
Template for object creation  new() constructor
Manager for member object  class predicates/facts
Instance Object: created individual thing
With different identity
With same attributes and methods
Person
"John", 85, 185, 110
NumberOfPerson
"Thomas", 78, 190, 150
Name
Age
Length
Weight
"Anna", 65, 175, 130
"Lidy", 55, 160, 123
NumberOfPerson = 4

5. Classes and Objects OOP in Visual Prolog
Class file(*.cl): declaration of public method
class-wide predicates and facts
Interface file(*.i): declaration of public method
Instance object’s predicates and facts
Prolog file (*.pro): actual implementation
Actual implementation of public method
Private method declaration and implementation
Person
getNumberOfPerson() …
getNumberOfPerson() :- …
getName() :-
setName(string Name) :-
NumberOfPerson
person.cl
Name
Age
Length
Weight
getName()
setName(string Name) …
person.i
person.pro

6. Classes and Objects Create a project ‘ch08class’
Add ‘person’ class to the project
Check ‘Create Interface’

7. Classes and Objects Build up ‘person’ class
In the ‘person.i‘ file, add 2 predicates
Add constructor to the ‘person.cl’ file +
person type +

8. Classes and Objects Add implementation to ‘person.pro’ file, Build!+
lowercase identifier +
constructor
member assignment

9. Classes and Objects Add menu/menu-item and connect
TaskMenu.mnu  Object/CreatObject
TaskWindow.win  onObjectCreateObject

10. Classes and Objects
Build / Try
Press <F5> if there’s an error.

11. Classes and Objects Add Dialog to create ‘person’ object
Create a package named ‘uiForms’
Create ‘createPerson’ dialog under uiForms

12. Classes and Objects Edit ‘createPerson‘ dialog
Add ClickResponder to createObject_ctl
name_ctl
createObject_ctl

13. Classes and Objects
In the TaskWindow.win  change the code in ‘onObjectCreateObject’ clause

14. Classes and Objects Build  Run
add a line to constructor in ‘person.pro’ file.
Build  Run

15. Classes and Objects Add class predicate to person class
Declare class predicate at the ‘person.cl’ file. +

16. Classes and Objects
Add implementation to ‘person.pro’  Run! +

17. Classes and Modules Module: non-object constructing class
Just a collection of class predicates.
No interface file is created for module.
Add ‘output.cl’ class to the project.
Uncheck ‘Create Interface’ option

18. Classes and Modules Add predicate to ‘output.cl’ file.
No type definition in the ‘output.cl’ file.
No type for output +
Overloading,
Polymorphism

19. Classes and Modules
Add implementation to ‘output.pro’ file. +

20. Classes and Modules Build / Run!
Change constructor in the ‘person.pro’ file.
Build / Run!

21. Holding Objects Garbage Collection Add 3 more menu options
Unreferenced object’s memory is reclaimed.
Keep the object reference for it being reachable.
Add 3 more menu options

22. Holding Objects
Edit ‘person.pro’ file. + +

23. Holding Objects
Edit ‘person.pro’ file. (continued) + +

24. Holding Objects Build / Run! Add declaration to ‘person.i’ file.
Test ‘Create Object’ menu item. +

25. Holding Objects Complete menu items
Add class predicate to ‘person.cl’ file.

26. Holding Objects Add implementation to ‘person.pro’ file. +
showAllPersons() :-
stdIO::write("These are the persons in the database.\n"),
showAllObjects(createdObjects).
class predicates
showAllObjects : (person* CreatedObjects).
clauses
showAllObjects([Head | Tail]) :-
stdIO::write("Name: ", Head:getName(), " with Number: ", Head:getNumber()),
stdIO::nl, !,
showAllObjects(Tail).
showAllObjects([]).

27. Holding Objects Add connection to menu items
TaskWindow.win  ‘Show All’ and ‘Show Single’
predicates
onObjectShowAll : window::menuItemListener.
clauses
onObjectShowAll(_Source, _MenuTag) :-
person::showAllPersons().
onObjectShowSingle : window::menuItemListener.
onObjectShowSingle(_Source, _MenuTag) :-
person::getAllNames(NamesList),
b_true = vpiCommonDialogs::listSelect("Select a name", NamesList, 0, Name, _Index), !,
person::showSinglePerson(Name).
onObjectShowSingle(_Source, _MenuTag) :- !. + +

28. Holding Objects
Add declaration to ‘person.cl’ file. +

29. Holding Objects Add implementation to ‘person.pro’ file. + clauses
getAllNames(NamesList) :-
getNames(createdObjects, NamesList).
class predicates
getNames : (person* CreatedObjects, string* NamesList) procedure (i, o).
getNames(ObjectsList, NamesList) :-
[Head | Tail] = ObjectsList, !,
Name = Head:getName(),
getNames(Tail, TailNamesList),
NamesList = [Name | TailNamesList].
getNames([], []) :- !.

30. Holding Objects Add implementation to ‘person.pro’ file. (cont) +
clauses
showSinglePerson(Name) :-
getData(Name, createdObjects, Number), !,
stdIO::write("You have selected: ", Name, " with number: ", Number),
stdIO::nl.
showSinglePerson(_Name).
class predicates
getData : (string Name, person* ObjectsList, unsigned Number) determ (i, i, o).
getData(Name, ObjectsList, Number) :-
[Head | Tail] = ObjectsList,
Name <> Head:getName(), !,
getData(Name, Tail, Number).
getData(_Name, ObjectsList, Number) :-
[Head | _] = ObjectsList,
Number = Head:getNumber().

31. Holding Objects Add code for ‘Delete Object’ menu item.
TaskWindow.win  onObjectDeleteObject
clauses
onObjectDeleteObject(_Source, _MenuTag) :-
person::getAllNames(NamesList),
b_true = vpiCommonDialogs::listSelect("Select a name", NamesList, 0, Name, _Index), !,
person::deletePerson(Name).
onObjectDeleteObject(_, _).

32. Holding Objects
Add declaration to ‘person.cl’ file. +

33. Holding Objects Add implementation to ‘person.pro’ file. + clauses
deletePerson(Name) :-
[Object | Tail] = createdObjects,
Name = Object:getName(), !,
createdObjects := Tail,
stdIO::write("Person ", Name, " has been deleted.\n").
deletePerson(Name), !,
createdObjects := [Object | createdObjects].
deletePerson(_).

34. Holding Objects
Rebuild All  Run!