Quintus Prolog Homepage WELCOME TO
Quintus Prolog
The Industry Standard
  Quintus Home > Quintus Objects
Quintus Objects is another<BR>useful tool for Quintus Prolog

Quintus Objects is another
useful tool for Quintus Prolog

Quintus Objects

Quintus Objects brings the advantages of object-oriented programming to Quintus Prolog, the world's most powerful system for creating stand-alone and embeddable Prolog-based applications.

Quintus Objects allows Prolog programmers to write efficient object-oriented programs in Prolog. The objects are updateable data structures whose slots can contain Prolog terms. Or, for increased efficiency, a slot can be constrained to hold a specific C-style type. Because objects are updateable, they offer an efficient alternative to storing modifiable data in the Prolog database.


  • Updateable objects
  • Classes with slots, messages and methods
  • Term classes - using ordinary Prolog terms as objects
  • Optional C-style types for slots
  • Private and protected slots restrict access to data
  • Direct slot access by fetch_slot/2 and store_slot/2
  • Automatic creation of get and put methods
  • Other methods defined by Prolog clauses
  • Single and multiple inheritance, resolved at compile-time
  • Class definitions and messages translated into Prolog code at compile-time


  • Convenient creation of efficient object-oriented programs, for Prolog programmers
  • Updateable objects offer an alternative to storing data in the Prolog database


  • Quintus Prolog 3.2, or later, on any supported QP platform