ch7-2008软件工程七章编码设计34

1、1（主讲（主讲 赵元哲）赵元哲）23456 数据结构的复杂性问题数据结构的复杂性问题 数据实时处理能力数据实时处理能力 数据库操作问题数据库操作问题78910111213141516171819202122nDefensive programmingDefensive programming is a form of defensive design intended is a form of defensive design intended to ensure the continuing function of a piece of software in spite to ensure

2、 the continuing function of a piece of software in spite of unforeseeable usage of said software. The idea can be of unforeseeable usage of said software. The idea can be viewed as reducing or eliminating the prospect of viewed as reducing or eliminating the prospect of Murphys LawMurphys Law having

3、 effect. Defensive programming techniques are used having effect. Defensive programming techniques are used especially when a piece of software could be misused especially when a piece of software could be misused mischievously or inadvertently to catastrophic effect.mischievously or inadvertently t

4、o catastrophic effect.nDefensive programmingDefensive programming is an approach to improve software and is an approach to improve software and source code, in terms of:source code, in terms of: General qualityGeneral quality - Reducing the number of software bugs and - Reducing the number of softwa

5、re bugs and blems. Making the source code comprehensibleMaking the source code comprehensible - the source code - the source code should be readable and understandable so it is approved in a should be readable and understandable so it is approved in a code audit.code audit. Making the so

6、ftware behave in a predictable manner despite Making the software behave in a predictable manner despite unexpected inputs or user actions.unexpected inputs or user actions.23n最常见的最常见的defensive programmingdefensive programming方法是加方法是加assertion(assertion(就是一种强制检查就是一种强制检查) )，比如比如: : 在访问一个内存地址之前，先检查指向那里的指针是否在访问一个内存地址之前，先检查指向那里的指针是否有效。有效。 在在win32win32平台上可以加入平台上可以加入，然后就可以，然后就可以用用assert(bool)assert(bool)这个函数。这个函数。 如果检查出这里有错，程序就会被中断在这行语句处，如果检查