第 10 章 定义不存在的错误

Chapter 10 Define Errors Out Of Existence

Exception handling is one of the worst sources of complexity in software systems. Code that deals with special conditions is inherently harder to write than code that deals with normal cases, and developers often define exceptions without considering how they will be handled. This chapter discusses why exceptions contribute disproportionately to complexity, then it shows how to simplify exception handling. The key overall lesson from this chapter is to reduce the number of places where exceptions must be handled; in many cases the semantics of operations can be modified so that the normal behavior handles all situations and there is no exceptional condition to report (hence the title of this chapter).

异常处理是软件系统中最糟糕的复杂性来源之一。处理特殊情况的代码在本质上比处理正常情况的代码更难编写，并且开发人员经常在定义异常时不考虑异常的处理方式。本章讨论了为什么异常对复杂性的贡献不成比例，然后说明了如何简化异常处理。本章总的主要教训是减少必须处理异常的地方的数量。在许多情况下，可以修改操作的语义，以便正常行为可以处理所有情况，并且没有要报告的特殊条件（因此，本章标题）。