任何有效的代码重复的原因？ [英] Any valid reason for code duplication?

问题描述

我目前正在审查一个非常古老的C ++项目，并看到很多代码重复。

I'm currently reviewing a very old C++ project and see lots of code duplication there.

例如，有一个类有5个MFC消息处理程序10个相同的代码行。或者有一个5行代码片段，用于非常特定的字符串变换。减少代码重复在这些情况下根本不是一个问题。

For example, there is a class with 5 MFC message handlers each holding 10 identical lines of code. Or there is a 5-line snippet for a very specific string transformation every here and there. Reducing code duplication is not a problem in these cases at all.

但我有一个奇怪的感觉，我可能会误会一些东西，并且最初有一个原因这种重复。

But I have a strange feeling that I might be misunderstanding something and that there was originally a reason for this duplication.

重复代码的有效理由是什么？

What could be a valid reason for duplicating code?

推荐答案

当我第一次开始编程时，我写了一个应用程序，我有一堆类似的功能，我包装在一个整洁的小20-30行功能...我为自己感到非常自豪，写这样优雅的代码。

When I first started programming, I wrote an app where I had a bunch of similar functionality which I wrapped up in a neat little 20-30 line function ... I was very proud of myself for writing such an elegant piece of code.

不久之后，客户端在非常特定的情况下，然后再次，然后又一次，然后又一次又一次...更改了过程（许多更多次）我的优雅的代码变成一个非常困难，黑客，越野车，高维护混乱。

Shortly after, the client changed the process in very specific cases, then again, then again, then again , and again, and again .... (many many more times) My elegant code turned into a very difficult, hackish, buggy, & high maintenance mess.

一年后，当我被要求做一个非常相似的事情时，我故意决定忽略DRY。我把基本过程放在一起，并生成了所有重复的代码。重复的代码被记录，我保存了用于生成代码的模板。当客户端请求特定的条件更改（像，如果x == y ^ z + b然后1 + 2 == 3.42），这是一块蛋糕。这是令人难以置信的容易维护&改变。

A year later, when I was asked to do something very similar, I deliberately decided to ignore DRY. I put together the basic process, and generated all duplicate code. The duplicate code was documented and I saved the template used to generate the code. When the client asked for specific conditional change (like, if x == y^z + b then 1+2 == 3.42) it was a piece of cake. It was unbelievably easy to maintain & change.

回想起来，我可能可以用函数指针和谓词解决很多这些问题，但是使用当时的知识，我仍然相信这个具体情况下，这是最好的决定。

In retrospect, I probably could have solved many of these problems with function pointers and predicates, but using the knowledge I had at the time, I still believe in this specific case, this was the best decision.

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