Software Engineering for Students A Programming Approach

SELF-TEST QUESTION
26.3 Which of the techniques suggest that XP is an incremental approach?
Summary 335
Frequent replanning means that the client should decide which function is most
important and should therefore be implemented next. The team estimates how long the
next stage of the project will take and gains agreement (or not) for it to proceed. This
way everyone takes responsibility for the planning.
Pair programming (see Chapter 28 on teams) is a novel idea, which sounds expensive,
but in reality saves time and improves quality by harnessing collaboration.
A maximum 40-hour week emphasizes that no good is achieved by continually working
too hard. In a conventional project, it is common to resort to overtime to remedy
delays. But this is usually a sign that something has gone wrong and the project is at
the start of the slippery slope that leads to a disaster. XP avoids the need for desperate
measures in two principal ways. First, continual testing prevents unpleasant surprises.
Second, frequent releases means that any planning mistakes are quickly evident.
The provision of an on-site customer is quite radical. It stresses that meeting the user
requirements is so important that it needs continual special treatment – the permanent
involvement of a client representative – which, though time-consuming, saves time overall
because reworking is avoided.
The use of coding standards illustrates that some aspects of XP are quite rigorous.
Also the code is the paramount product of a project. Emphasis is placed on clear code,
rather than auxiliary documentation, such as UML diagrams.
It is important to realize that these techniques complement each other, so that it is
sometimes ineffective to use one without another. It is possible, but undesirable to use
one of the XP techniques on its own. This is because they complement each other – a
weakness in one practice is compensated by strength in another. For example, it would
seem expensive in time continually to refactor the design, but the practice of keeping
to a simple design ensures that refactoring is easy.
Summary
Agile methods are a range of lightweight techniques that subscribe to the agile
manifesto.
XP is one agile method with its own values and techniques. The values are communication,
simplicity, feedback and courage. The twelve techniques include pair
programming, test-driven development and continual refactoring.
XP makes the coding, rather than any other documentation, the center of the
product.