Có 40+ tài liệu thuộc chủ đề "Douglas Bell"
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13.1 Compare the factoring Inline Class with the factoring Extract Class.. the use of the phrase “is-a” in the description of an object (or class) signifies that it is probably an inheritance relationship.. the use of the phrase “has-a” indicates that there is no inheritance relationship.. In the game, several of the classes – Defender, Alien, Laser and Bomb –...
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This means that it should be possible to combine language features freely. This means that these two groups must be treated differently, for example, when they are inserted into a data struc- ture. It is no easy matter to design a language that is simple, clear and orthogonal. Indeed, in some cases these goals would seem to be incompatible with...
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Thus it is largely the responsibility of the programmer to ensure that pro- cedures and functions do not have side effects. Most pro- gramming languages do not prevent programmers from directly accessing and modify- ing data objects (global data) defined outside of the local environment of the method.. Along with pointers and the goto statement, global data has come to...
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14.4 The benefits are program clarity, better modeling of the problem, compile- time checking and run-time checking.. 14.5 This is a case of expressive power and convenience versus fast per- formance.. Creating an object is also known as instantiating an object.. We will use the example of the cyberspace invaders game, Figure 15.1, to illustrate encapsulation. 15.2 ● Encapsulation 15.1...
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exploit the common features of the classes. class Sprite. You can see that the variables and methods within this class are relevant to all the game objects. You will also notice that the variables declared at the head of the class that were described as public , are now described as protected . This means that they are accessible from...
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15.1 public void moveDown(int amount. 15.2 public int yCoord { get. 15.3 Methods: creditAccount, debitAccount, calculateInterest Properties: currentBalance, name. 15.4 class Stack. 15.3 Suppose that you were asked to design a new programming language for software engineering:. 15.4 Explain what the term modularity means. 15.5 Assess the generics feature.. 15.6 Argue for and against pointers in a programming language.. 15.7...
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228 Chapter 16 ■ Programming in the large. implement every method described in the interface. See for example Figure 16.2. For example, sup- pose we wanted to describe an interface for a BetterStack that is a subclass of the Stack interface described above. it is textual (though we could think of tools to convert the text into graphics). it is...
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some systems, when a user error arises, again it is the role of the software to cope. This chapter explores measures that can be taken to detect and deal with all types of computer fault, with emphasis on remedial measures that are implemented by software.. Software fault tolerance is concerned with trying to keep a system going in the face...
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In Java, the method parseInt can be written as follows:. You can see that in the heading of the method the exception that may be thrown is declared, along with the specification of any parameters and return value. If this method detects that any of the characters within the string are illegal, it executes a throw instruction. Alternatively the try-catch...
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It is a study in paranoia:. For a more detailed treatment of some of the topics described in this chapter, see:. 17.5 The answer depends on the particular software. at the start of the method.. 17.8 Control continues down the program, which dangerously tests the value of the information returned by parseInt.. 17.9 The precondition is assert oldCount >. We...
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We begin this chapter by discussing the general problem of testing – and discover that there is a significant problem. We consider approaches called black box and white box testing.. In addition, each component of the software ideally has an individual specification that is derived from architectural design. Any such problems should, of course, be detected and remedied by verification...
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The situation is well summed up by one of computing’s gurus, Dijkstra, in his famous remark, “Testing can only show the pres- ence of bugs, never their absence.” This has been (anonymously) rephrased as, “Just because you have never seen a mermaid doesn’t mean that they don’t exist.” It can be reassuring to adopt the view that a test that...
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20.6 Suggest features for software tools that could assist in using each of the following techniques:. Full of practical advice and case studies, jointly authored by one of the industry gurus, all you ever wanted to know about inspections is explained in: Tom Gilb and Dorothy Graham, Software Inspection, Addison-Wesley, 1993.. The waterfall model is an established approach that dominated...
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298 Chapter 22 ■ The spiral model. The distinctive feature of the spiral model is that it makes explicit the idea of risk.. The spiral model explicitly recognizes that there are uncertainties associated with software development and that they should be dealt with as carefully as possible. the client changes some of the requirements. one of the component tasks of...
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Smalltalk is a language that can be used to pro- totype adventurous GUIs with very little programmer effort. A drawback of Smalltalk is that it can be a massive consumer of processor time and memory, so that after pro- totyping it may be necessary to rewrite the system in some other language. 23.6 ● Rapid prototyping techniques. a stage of...
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Top- down starts with the user interface and implements each of the various functions in a breadth-first fashion. The stages of the use case approach are:. 24.8 ● Discussion. 24.4 Create an outline plan for developing each of the systems in Appendix A, using an incremental approach.. visibility of the development to developers and clients.. 24.7 Identify the main goals...
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328 Chapter 25 ■ Open source software development. 25.1 Can you think of any situations or products for which the open source procedure might be most appropriate?. 25.2 Can you think of examples of situations in which open source development of prod- ucts might be unwise?. 25.3 Assess whether open source would be suitable for each of the developments given...
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The second aim of the UP recog- nizes that there are always risks associated with a development. Examples are changes in user requirements and deadline overruns for components of the software. To meet its aims, the UP makes use of a number of techniques including use cases, iteration and emphasis on the architecture of the software.. (Use cases were discussed...
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Always there are queries, because of the difficulty of specifying interfaces precisely. New people join the team and have to be helped to understand what the software is for, what has been done and why the structure is as it is. But, eventually, the communication overheads will become overwhelming, and the project will actually slow down. The graph looks like...
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predicting qualities of software that is about to be developed. making judgments on the quality of a piece of software that has been developed. monitoring and improving the software development process. The simplest measure of software is its size. Two possible metrics are the size in bytes and the size in number of statements. But a longer program does not...