计算机专业英语（第二版）孙建忠电子教案 Chapter6.ppt

Computer English Chapter 6 Software Engineering 6.2 The Software Life Cycle The classic life cycle is the oldest and the most widely used paradigm for software engineering. However, over the past few years, criticism of the paradigm has caused even active supporters to question its applicability in all situations. Among the problems that are sometimes encountered when the classic life cycle paradigm is applied are: 传统的生存期是软件工程中使用最早的，也是应用最广泛的模型，尽管如此，最近几年出现的对模型法的批评，甚至使那些积极的支持者也质疑它是否适合于所有情况中。下面是传统的生存期模型有时会遇到的问题： 6.2 The Software Life Cycle ·Real projects rarely follow the sequential flow that the model proposes. Iteration always occurs and creates problems in the application on the paradigm. ·It is often difficult in the beginning for the customer to state all requirements explicitly. The classic life cycle requires this and has difficulty accommodating the natural uncertainty that exists at the beginning of many projects. ·The customer must have patience. A working version of the program(s) will not be available until late in the project time span. A major blunder undetected until the working program is reviewed can be disastrous. ·真正的项目很少依照模型所提出的顺序流程来实现，时常会出现迭代，这样会在模型的应用中制造问题。 ·要求用户在开始时明确指出全部要求往往是困难的。传统的生存期却要求如此，这样很难适应许多项目在设计之初就存在的不确定性。 ·这种模型要求用户必需有耐心，因为程序的工作版本直到整个项目的后期阶段才可用。到验收程序时才发现的一个大错会是一个灾难。 6.2 The Software Life Cycle Each of these problems is real. However, the classic life cycle paradigm has a definite and important place in software engineering work. It provides a template into which methods for analysis, design, coding, testing, and maintenance can be placed. The classic life cycle remains the most widely used procedural model for software engineering. While it does have weaknesses, it is significantly better than a haphazard approach to software development. 所有这些问题都是实际存在的，尽管如此，传统的生存期范例在软件工程中仍占有明显的重要位置，它提出了一个包含分析、设计、编码、测试和维护方法的模板。传统的生命周期仍然是软件工程中应用最广泛的程序模型，尽管它有一些不足，但它仍显著好过杂乱无意识地进行软件开发。 6.3 Prototyping New Words Expressions: prototyping n. 原型法 g