调试器，敏捷过程的害群之马

当你习惯了测试驱动的开发（Test-Driven Development，TDD）之后，你会发现自己越来越少地使用调试器（debugger）——如果你发现程序里有什么问题，你不应该用调试器去抓bug，而是应该用一个单元测试用例来揭示问题的所在。由于存在细粒度、完整覆盖的单元测试用例，每个bug都相当清晰，于是很少会需要各种巧妙的调试手段了。

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Uncle Bob's Software Craftsmanship Corner

Debuggers are a wasteful Timesink

by Robert C. Martin
November 29,2003

Summary
As debuggers have grown in power and capability,they have become more and more harmful to the process of software development.

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Debuggers have become immensely powerful. A good debugger is a very capable tool. With it,an experienced developer can step through very complex code,look at all the variables,data structures,and stack frames; even modify the code and continue. And yet,for all their power,debuggers have done more to damage software development than help it.

Since I started using Test Driven Development in 1999,I have not found a serious use for a debugger. The kinds of bugs I have to troubleshoot are easily isolated by my unit tests,and can be quickly found through inspection and a few judiciously placed print statements.

I teach a lot of classes in C++,Java,C#,TDD,XP,Patterns,etc. In those classes I often have the students write code. It is not unusual for me to find a student with his or her nose buried in a debugger,painstakingly stepping from line to line,examining variables,setting breakpoints,and generally wasting time. The bug they are tracking could be found through simple inspection of the code.

I consider debuggers to be a drug -- an addiction. Programmers can get into the horrible habbit of depending on the debugger instead of on their brain. IMHO a debugger is a tool of last resort. Once you have exhausted every other avenue of diagnosis,and have given very careful thought to just rewriting the offending code,*then* you may need a debugger.