程序验证与Ada语言

设计Ada的目标之一旨在提供一种语言,能够促进可靠程序的生产。为获得较高的可靠性,一项重要的技术便是程序验证。本文从这一角度,评论Ada语言的设计,并就Ada程序验证提出某些具体方法。     

Ada与图形核心系统

图形核心系统(GKS)是一种通用的、独立于设备的二维图形系统。由国际标准化组织(ISO)[ISO 1982]和美国标准化协会(ANSI)主持的该系统的标准化工作,现在已进入了最后阶段。每一项GKS标准化工作都与程序设计语言的联编(binding)有关。它为GKS的实现提供了特定语言的标准化接口。当前在该项标准化工作的建议草案中,把Ada语言联编到ANSI GKS[ANSI 1985]。本文介绍产生联编到ANSI GKS的Ada语言和用Ada实现GKS(GKS/Ada)的研究工作。这与建议的Ada语言联编的草案要求相一致。这将是第一个展示标准化的Ada图形能力的系统。     

一种Ada83服务性任务向Ada95保护对象变换的方法

任务是Ada语言支持并发程序设计的基础,它提供了一种进程同步和通信的良好机制.但也存在一类被动的、专为其他任务服务的服务性任务.服务性任务的存在增加了系统的负担,降低了系统的性能.如果能将服务性任务变换为保护对象,则可以明显地提高系统的性能,减少维护的费用.该文提出了一种在源程序级将Ada83服务性任务变换为Ada95保护对象的方法.先给出服务性任务应满足的条件、识别和表示服务性任务的方法,最后讨论此方法的可行性.与其他方法相比,此方法具有假设条件少、识别和变换效率高以及容易验证等特点.     

VAX／VMS Ada异常的实现方法

程序单元的运行可能会遇到程序无法正常运行下去的出错(或例外)情况。在Ada语言中引入了异常机制,以处理程序运行中出现的这些错误或例外情况。异常机制是Ada语言程序运行期间处理异常的方法和手段,是Ada语言的一个重要特点,也是实时程序设计所要求的重要设施。本文主要讨论Ada异常机制的语义、以及VAX/VMS Ada实现这一机制使用的数据结构和实现方法。     

从软件工程看Ada程序设计语言

Ada语言是一种新的现代高级程序设计语言,它代表了现代高级程序设计语言的发展水平。本文从软件工程的角度分析了Ada语言所具有的主要特征和这些特征对软件工程的支持及贡献。目的在于更深入地认识Ada语言及其作用,促进在软件工程领域中更好地开发应用Ada语言。     

Ada编译中若干问题

Ada是由Jean D.Ichbiah等人代表美国国防部设计的一个新的系统程序设计语言,我们提出了Ada编译程序的一种结构,它分为(不依赖于机器的)前端部分与依赖于机器的后端部分。文章讨论了解决前端设计某些问题的若干方法。最后简要地介绍了中间语言DIANA,它是专门为表示Ada程序的中间形式而设计的。     

试评Ada语言

本文分析了Ada语言的主要成分,Ada语言在下列方面有明显的优点: 1.它有模块化的功能和精确的数据描述,从而提高了程序的可靠性; 2.它具有适当而齐全的数据结构和运算控制结构,可以面向广泛的应用领域; 3.它在语法和语义两方面都特别适合于大量应用问题,提高了程序的开发效率; 4.它是第一个与软件支撑环境结合在一起的程序设计语言。为了适应广泛的应用领域,Ada语言在简明性和程序的执行效率两方面付出了代价。     

支撑程序包用户指南专辑 前言

<正> Ada是一种用于大型和实时嵌入式系统的设计和实现的高级语言。Ada的特点之一是其可扩充性。这不仅体现于APSE的开放式,也体现予Ada语言本身。Ada本身只定义了必需的数据结构和控制结构以及有限的高级I/O,更多的设施都可以Ada程序包的形式进行实现所允许的扩充。Ada的分别编译、库单元和程序包机制保证这种扩充可以为所有的Ada用户共享。     

基于网语言的Ada程序局部性质的分析和验证

旨在研究利用网语言讨论Ada程序性质和由此而引起的Ada网的状态爆炸问题.研究了Ada网的同步合成与分解,讨论了它们的语言性质,并利用这一结果分析和验证了Ada程序的安全性和活性,从而为复杂的Ada程序的分析与验证提供了一个新的有效途经.     

时序Ada网的语言性质

在Ada网的基础上，利用时序Petri网为Ada任务程序建模，提出了时序Ada网的概念，利用时序Ada网，可以很好地反映Ada程序的公平性和原子性要求及描述程序的需求，规范，对时序Ada网的语言性质进行分析，结论表明时序Ada网所能接受的网语言能完整地刻画程序的动态行为和时序关系，有助于对程序性质的分析和验证。     

Intraprogram documentation

Three kinds of documentation are examined: summary documentation describes the intent and nature of the program; detail documentation gives all the information the user needs to put the program to work; intraprogram documentation is information written into the program to inform the user or programmer. The need for intraprogram documentation occurs at four different times: in the initial design period; during debugging; as the program and system evolve; when it is necessary to adapt the program to other systems There are several means for providing intraprogram documentation. There are comments which can be placed in the header, on each line, at the beginning and end of a subroutine. Also noted is the important use of space for making the comments easier to read and for separating chunks of the program. Special symbols serve the same purpose. Examples are provided to bring home these points.     

《C语言程序设计》课程教学改革建议

《C语言程序设计》课程作为高校计算机专业一门重要的学科基础课,对于学生程序实践能力的培养具有重要意义。然而在课程教学中往往存在学生失去兴趣、上课听懂但不能独立编写程序、课堂所学与实际应用需求脱节等现象。以上述问题为出发点,从改进教学内容和方法、加强实践教学,以及改革考核方式等方向进行探索和研究,以提高课程教学质量,增强学生的学习兴趣和编程实践能力。     

A Multimedia Constraint System1

The MADE constraint system provides excellent opportunities to introduce constraints in a multimedia application. Multimedia applications are not only a good place to experiment with constraint systems; constraints in a multimedia environment are almost indispensable. Due to the overwhelming amount of data and the number of relations between several parts of this data, multimedia applications almost demand the support of a constraint management system. The MADE constraint system combines the object oriented programming paradigm, inherited from the mC++ language, the declarative constraint programming paradigm and the special requirements imposed upon the constraint system by the multimedia environment. Among other things, the MADE constraint system provides parallel satisfaction techniques; several constraints may be solved simultaneously and this satisfaction process is performed in parallel with the application. This not only reduces the time needed to solve the constraints, it also allows the multimedia application to proceed with its presentation while (beneath the surface) the constraints are maintained. This not only holds for the parts of the presentation that are not constrained at all, but also for those parts that are. Furthermore, the constraint system is transparent to the multimedia application; no special coding or preparation of the objects in the application is necessary. Constraints can be added later to the application without much work. Besides that, it is also possible to add and remove constraints at runtime; objects may be constrained for only a period of the time the application is running.     

服务机器人分层式图形化编程平台

为了简化服务机器人编程流程,针对服务机器人任务规划特点,基于分层编程的理念,设计了一套简易图形化编程平台。平台由基本模块层、执行协调层、任务规划层3层组成,用户在不同层次采用不同编程方式,兼顾了编程效率和执行效率。同时,提供了友好的图形化编程界面,方便机器人编程。在交龙服务机器人上的编程实验验证了该平台编程的有效性和便捷性。     

A Stochastic-Goal Mixed-Integer Programming approach for integrated stock and bond portfolio optimization

We consider a Stochastic-Goal Mixed-Integer Programming (SGMIP) approach for an integrated stock and bond portfolio problem. The portfolio model integrates uncertainty in asset prices as well as several important real-world trading constraints. The resulting formulation is a structured large-scale problem that is solved using a model specific algorithm that consists of a decomposition, warm-start, and iterative procedure to minimize constraint violations. We present computational results and portfolio return values in comparison to a market performance measure. For many of the test cases the algorithm produces optimal solutions, where CPU time is improved greatly.     

Distributed Pair Programming: A Systematic Literature Review

ContextGeographically distributed teams have adopted agile practices as a work strategy. One of these practices is Distributed Pair Programming (DPP). DPP consists in two developers working remotely on the same design, algorithm or code.ObjectiveIn this paper we sought to identify and synthesize papers that describe and analyze DPP both from teaching and practice perspectives.MethodWe conducted a Systematic Literature Review to search for empirical evidence in eight digital libraries.ResultsMost of the 34 DPP primary studies identified explore DPP from a teaching perspective. We found that DPP requires a specific infrastructure, but the existing studies do not explore the impact of the distribution in the details. There are many tools proposed that support DPP practice, but few of them are evaluated within a software development team.ConclusionWe need more studies that explore the effects of Pair Programming in the context of Distributed Software Development, such as coordination and communication. Most of the studies do not empirically evaluate DPP in industry. There is also a need to propose guidelines to use DPP in industry and as a teaching strategy.     

Students working for students on programming courses

In this paper we offer a report on a university-level programming laboratory course that has been designed on top of a programming library. The course enforces soft skills, such as code inspection and team working, sharpens implementation skills and creates a bridge between introductory, language-specific instruction and senior-year full-blown programming projects that are usually large but not attending to soft skills. Quite as importantly, it has also delivered a working research tool.     

C语言程序设计学习中的问题及策略初探

本文首先分析了C语言程序设计学习中存在的一些问题,针对这些问题,对如何提高C语言程序设计的学习效率给出了一些看法和建议。     

交换编程——极限编程的延伸实践

结对编程是一种编程组队方法,在这种方法中要求两个程序员使用一台电脑在一起工作完成同一个任务。在软件开发中关于结对编程的价值正在进行着争论。目前在这个领域大量的知识都是离散的和无条理的。回顾这些可以看到绝大多数这方面的实验研究都是在大学环境中进行的。几乎没有在真实软件开发项目中详细审查下的结对编程被已存在的系统化实验研究过。因此,假设目前仍然没有纯粹的经验验证这种优势的存在。由于结对编程在表象上给人以浪费一个开发人员的感觉,所以,在很多软件企业中,很难得到推广实施。在本文的报告中,我们给出了一种有别于结对编程和传统的单人编程的团队组织形式,这种形式融合了结对编程促进团队内相互交流的好处,保持了团队的稳定性,同时采用了传统单人编程的形式,不给人以浪费人力的感觉。     

A Safe Relational Calculus for Functional Logic Deductive Databases

In this paper, we present an extended relational calculus for expressing queries in functional-logic deductive databases. This calculus is based on first-order logic and handles relation predicates, equalities and inequalities over partially defined terms, and approximation equations. For the calculus formulas, we have studied syntactic conditions in order to ensure the domain independence property. Finally, we have studied its equivalence w.r.t. the original query language, which is based on equality and inequality constraints.