OBJECT-ORIENTED ANALYSIS AND DESIGN CONCEPTS OF SPACE AND TIME Phần 4 ppsx

OBJECT-ORIENTED ANALYSIS AND DESIGN 29

features it does have are sufficient to support the desired programming styles in the

desired application areas’ (1988, p. 11). Object-oriented programming languages are

still being developed and it is expected that new languages will emerge, acquiring

new features rapidly.

From the mid-1970s onwards the research and development in artificial intelligence

(AI) programming environments have also influenced the object-oriented paradigm.

LISP is one of the main programming languages used in AI systems, and several

object-oriented extensions of LISP have been created. LOOPS, Common LOOPS,

FLAVOURS, KEE, ART and New FLAVOURS are some examples in which a

semantically ample form of inheritance is proposed that differs from the one

encountered in most object-oriented programming languages such as Smalltalk. Here

values, in particular default values, can be inherited as well as attribute names. Graham

assures his readers that, from his point of view, ‘AI people have got it right and that

this kind of inheritance will gradually penetrate the world of object-oriented

programming’ (1994, p. 78).

With the maturing of the concepts in object-oriented programming languages and

their practical use in different application contexts, research interests have diversified,

focusing on object-oriented design methods:

Object-oriented design is a method of design encompassing the process of object￾oriented decomposition and a notation for depicting both logical (class and object

structure) and physical (module and process architecture) as well as static and dynamic

models of the system under design. (Booch, 1994, p. 39)

Significant debate has occurred in this research area, mainly concerning whether an

object-oriented design method can be intrinsically independent of any programming

language, or whether current design methods are clearly attached to specific object￾oriented programming languages. Most object-oriented design methods reveal the

influence of Booch’s pioneering work (Booch, 1986). In his original proposal, Booch

suggested a design method based upon some features of the ADA programming

language, using an object-oriented style. GOOD2

and HOOD3

are examples of ADA￾derived methods that enforce the top-down hierarchical decomposition approach

among objects but without supporting inheritance and polymorphism.

Also influenced by Booch’s work, OOSD4

provides a hybrid, low-level notation for

logical design of object-oriented methods in general. Although designed to be language

independent, OOSD has not been extended to a consistent object-oriented notation

due to its inability to deal with complex data structures and large numbers of methods.

OODLE5

is another example of a language-independent notation which advocates four

interrelated diagrams in order to support the Shlaer-Mellor approach to object-oriented

design. Booch’s revised design method (Booch, 1991, 1994) gives probably the most

2

General Object-Oriented Design method developed at NASA.

3

Hierarchical Object-Oriented Design method developed at the European Space Agency.

4

Object-Oriented Structure Design introduced by Wasserman, Pircher and Muller (1990).

5

Object-Oriented Design LanguagE is a design-specific component of the Shlaer-Mellor method (Shlaer

and Mellor, 1988).