Lehre in der Abteilung Dialogsysteme

Project SCOOL

Dr. Kenji Hanakata

SCOOL (Stuttgart C- based Object Oriented Language, pronounced like "school") is not just another object-oriented programming language. SCOOL is an interactive, open, persistent object-oriented language with many AI and DB features for large applications.

Main features of SCOOL

Software System Features in General

• Software integrity through SCOOL's Open Architecture
  SCOOL-browsers and other graphic interfaces are based on the X Window System. Other software is integrated through C, C++ and shell interfaces.
  
  
• Portability
  SCOOL is implemented in standard C and C++ so that it runs not only on Unix but also on other OSs.

Object-oriented Language Features

• No distinction between class and instance
  Distinction between class and instance, quite common in other OOPLAs, is not made in SCOOL. Both are special cases of SCOOL's objects. Any SCOOL object can have slot definitions, slot values, methods and descendants.
  
  
• Worlds of objects
  SCOOL's objects are clustered into a number of worlds which serve as an additional taxonomic feature for global structuring and classification of a large number of objects.
  
  
• Persistent objects
  Objects survive the termination of a SCOOL session unless they are explicitly killed or bound to variables whose scope decides their termination. Partial conservation of objects in a SCOOL specific object database are crucial for efficient evolutional programming development (as opposed to Smalltalk's images).
  
  
• Virtual object management
  SCOOL can afford a practically unlimited number of objects through its own virtual memory management. The content dependent virtual object management turned out to be much more efficient than that by virtual memory of OS.
  
  
• Multiple dynamic inheritance
  Multiple inheritance of object properties allows the multiple view of objects, while dynamic inheritance enables modal context sensitive message processing.
  
  
• unification between message and method-filter
  Like in Prolog, variable bindings a in method activation are bidirectional so that a method returns multiple values through variable-variable bindings specified by the unification.
  
  
• Back-up, undo, not-undo
  Back-up and (not-)undo can be restricted by the scope specified through messages and heterarchcal inheritance relations. The not-undo within an undo-scope increases the back-up efficiency as it is needed in Prolog.
  
  
• Coreference between objects
  An object can refer another object on the object level as well as on its property level. This coreference feature increases the flexibility of resource sharing orthogonal to the resource sharing by inheritance.
  
  
• Access control
  Access control for read, write and execution (rwx) is made on the level of worlds, objects and its properties (slot definition, slot value, method) in addition to the private/public feature of the latter level.
  
  
• Segment variable, single variable
  Unlike Lisp and Prolog, a segment variable in corporation with multiple-value assignment and variable-binding in unification substantially increases the power of method invocations.
  
  
• Versatile primitives for string and list processing
  These primitives enables SCOOL programmers consistently to manipulate any data from letters, texts to complex objects without changing the representation style depending on the levels of data.
  
  
• Hypertext supported by knowledge objects
  The integration of active objects into a text leads to a fine grained flexible manipulation of texts in terms of dynamic access and generation in corporation with graphic interface. SCOOL manual is written in Hypertext (in preparation.)
  
  
• Japanese language features

(CADYS)