The main thing with the sub-class mechanism as found in languages like C++, SIMULA and Smalltalk is its possibility to express specializations. A general class, covering a wide range of objects, may be specialized to ...
详细信息
Two design approaches for the same Ada language project are examined. The first approach uses an object-oriented design, while the second approach uses a finite-state machine that draws heavily on underlying system se...
详细信息
Two design approaches for the same Ada language project are examined. The first approach uses an object-oriented design, while the second approach uses a finite-state machine that draws heavily on underlying system services. Both approaches satisfy the basic requirements of an Ada language project and are evaluated with regard to performance, portability, and reusability.
The benefits of data abstraction are ensured using encapsulation, by preventing an object from being manipulated except via its defined external operations. In many popular languages, however, the introduction of inhe...
详细信息
The benefits of data abstraction are ensured using encapsulation, by preventing an object from being manipulated except via its defined external operations. In many popular languages, however, the introduction of inheritance severely compromises encapsulation by exposing implementation details to inheriting clients. Moreover, in most object-orientedlanguages, the use of inheritance in the construction of software components is exposed to clients, so that changes to the inheritance hierarchy cannot be made safely. In this paper, we examine the interaction between inheritance and encapsulation and explore various ways in which implementation details can be exposed via inheritance. We analyze two common multiple inheritance models and explore a third model that fully supports encapsulation. We develop requirements for full encapsulation, which we are exploring in the Common objects language.
Two processors are presented that use parallel SIMD (single-instruction/multiple-date) data paths to support common graphics data structures as primitive operands in arithmetic expressions. A variant of the C language...
详细信息
ISBN:
(纸本)0818608056
Two processors are presented that use parallel SIMD (single-instruction/multiple-date) data paths to support common graphics data structures as primitive operands in arithmetic expressions. A variant of the C language has been implemented to allow high-level language coding of user applications on these processors. High-level programming support is designed into the processor architecture that implements parallel object data typing and parallel conditional evaluation in hardware.
A description is given of the object executive (OX), a run-time environment that lets application programs perform parallel processing. applications using OX manage data as a set of objects and initiate data processin...
详细信息
ISBN:
(纸本)0818608021
A description is given of the object executive (OX), a run-time environment that lets application programs perform parallel processing. applications using OX manage data as a set of objects and initiate data processing by sending messages to objects. Competition for resources is resolved by means of message priorities. An integer search program is given as an example of speculative parallelism using OX.
The authors have designed a prototype framework for a software-engineering environment and implemented it using the Ada programming language. It currently runs under VAX/VMS**2. An architectural description of the pro...
详细信息
ISBN:
(纸本)0818608064
The authors have designed a prototype framework for a software-engineering environment and implemented it using the Ada programming language. It currently runs under VAX/VMS**2. An architectural description of the prototype is presented along with lessons learned, and future plans for extending the framework's functionality.
A number of individual concepts embodied in Eiffel were present in previous languages, notably Simula 67, Ada and Alphard. However the design has brought in many new contributions. From the language standpoint, one ma...
详细信息
Visual language is a recently developed research field. Three visual languages, PLAY, VICON, HI-VISUAL, are reviewed. PLAY is an iconic programming system for children. VICON, using generalized icons, is a visual lang...
详细信息
Visual language is a recently developed research field. Three visual languages, PLAY, VICON, HI-VISUAL, are reviewed. PLAY is an iconic programming system for children. VICON, using generalized icons, is a visual language for designing icon-oriented software systems on a Lisp machine. HI-VISUAL utilizes both icons and process icons for visual interaction. The concepts of entity-relationship (ER) diagrams, primitive picture entities, picture relationships, and picture grammars have been applied to the generation of visual languages. Illustrative examples are presented. A high-level description of a two-level visual language system is proposed using either string description or ER diagram description. Illustrative examples are given. The advantages of ER diagram descriptions are pointed out. The result may have useful applications in robotics, artificial intelligence, expert systems, picture processing, pattern recognition, two-dimensional grammars, region filling, knowledge engineering and pictorial database design.
Although Smalltalk is simple, this programming language embodies many powerful concepts. To develop applications, users simply add building blocks. In this way, Smalltalk easily accommodates the changing needs and req...
详细信息
Although Smalltalk is simple, this programming language embodies many powerful concepts. To develop applications, users simply add building blocks. In this way, Smalltalk easily accommodates the changing needs and requirements of its users. Smalltalk is an object-oriented rather than procedural language. Unlike other object-orientedlanguages, Smalltalk retains a purely object-oriented model. objective C, Ada and Lisp, by contrast, are hybrids that force programmers to switch between object-oriented and more traditional programming styles. Smalltalk has much in common with other languages aimed at artificial intelligence applications. Like Lisp, Smalltalk does not distinguish between code and data, which means that programmers can create a program that constructs another program dynamically. This ability is important in AI applications, in which a program generates and tests solutions and does not simply execute algorithms.
Emerald is an object-based language for programming distributed subsystems and applications. Its novel features include 1) a single object model that is used both for programming in the small and in the large, 2) supp...
详细信息
Emerald is an object-based language for programming distributed subsystems and applications. Its novel features include 1) a single object model that is used both for programming in the small and in the large, 2) support for abstract types, and 3) an explicit notion of object location and mobility. This paper outlines the goals of Em-erald, relates Emerald to previous work, and describes its type system and distribution support. We are currently constructing a prototype implementation of Emerald.
暂无评论