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Pair programming (sometimes referred to as peer programming) is an agile software development technique in which two programmers work as a pair together on one workstation. One, the ''driver'', writes code while the other, the ''observer'', ''pointer'' or ''navigator'',〔"One of the programmers, the driver, has control of the keyboard/mouse and actively implements the program. The other programmer, the observer, continuously observes the work of the driver to identify tactical (syntactic, spelling, etc.) defects, and also thinks strategically about the direction of the work."〕 reviews each line of code as it is typed in. The two programmers switch roles frequently. While reviewing, the observer also considers the "strategic" direction of the work, coming up with ideas for improvements and likely future problems to address. This frees the driver to focus all of his or her attention on the "tactical" aspects of completing the current task, using the observer as a safety net and guide. ==Advantages== ;Economics :Pairs spend about 15% more time on programs than individuals. However, the resulting code has about 15% fewer defects. Along with code development time, other factors like field support costs and quality assurance also affect the expenses. IBM reported spending about “$250 million repairing and reinstalling fixes to 30,000 customer-reported problems”. Pair programming significantly reduces these expenses by reducing the defects in the programs. ;Design quality :A system with two programmers possesses greater potential for the generation of more diverse solutions to problems for three reasons: (1) the programmers bring different prior experiences to the task; (2) they may access information relevant to the task in different ways; (3) they stand in different relationships to the problem by virtue of their functional roles. In the attempt to share goals and plans, the programmers must overtly negotiate a shared course of action when a conflict arises between them. In doing so, they consider a larger number of ways of solving the problem than a single programmer alone might do. This significantly improves the design quality of the program as it reduces the chances of selecting a poor method.〔Flor, N.V. and E.L. Hutchins. Analyzing Distributed Cognition in Software Teams: A Case Study of Team Programming During Perfective Software Maintenance. ''Proceedings of the Fourth Annual Workshop on Empirical Studies of Programmers''. 1991: Ablex Publishsing Corporation.〕 ;Satisfaction :In an online survey of pair programmers, 96% of them stated that they enjoyed their work more than when they programmed alone. Additionally, 95% of the surveyed programmers stated that they were more confident in their solutions when they pair programmed. A correlation exists between satisfaction among programmers and their confidence in the code i.e. the pairs enjoy their work more because they are more confident in it.〔Laurie Williams, Robert R. Kessler, Ward Cunningham, Ron Jeffries. “Strengthening the Case for Pair Programming.” ''IEEE Software''. IEEE Software, July–Aug. 2000. Web. 4 October 2013〕 ;Learning :Knowledge is constantly shared between pair programmers, from tips on programming language rules to overall design skill.〔Richard L. Upchurch, Laurie Williams. “In Support of Student Pair Programming.” ''ACM SIGCSE''. ACM Publications, March 2001. Web. 4 October 2013〕 In "promiscuous pairing", each programmer communicates and works with all the other programmers on the team rather than pairing only with one partner, which causes knowledge of the system to spread throughout the whole team.〔 Pair programming allows the programmers to examine their partner's code and provide feedback which is necessary to increase their own ability to develop monitoring mechanisms for their own learning activities.〔 ;Team-building and communication :Pair programming allows team members to share problems and solutions quickly making them less likely to have hidden agendas from each other. This helps pair programmers to learn to communicate more easily. “This raises the communication bandwidth and frequency within the project, increasing overall information flow within the team.”〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Pair programming」の詳細全文を読む スポンサード リンク
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