确保文档保持最新状态的一种好方法是，在将更改提交到修订控制系统之前需要花费几分钟，以扫描该提交的所有更改。确保文档中正确反映了每个更改。这些预先提交的扫描还将检测其他一些问题，例如意外地将调试代码留在系统中或无法修复 TODO 项目。
关于维护文档的最后一个想法：如果注释比代码更高级，更抽象，则注释更易于维护。这些注释不反映代码的详细信息，因此它们不会受到代码更改的影响；只有整体行为的变化才会影响这些评论。当然，正如 第十三章：注释应该描述代码中不明显的内容 所讨论的那样，某些注释的确需要详细和精确。但总的来说，最有用的注释（它们不只是重复代码）也最容易维护。
One good way to make sure documentation stays up to date is to take a few minutes before committing a change to your revision control system to scan over all the changes for that commit; make sure that each change is properly reflected in the documentation. These pre-commit scans will also detect several other problems, such as accidentally leaving debugging code in the system or failing to fix TODO items.
One final thought on maintaining documentation: comments are easier to maintain if they are higher-level and more abstract than the code. These comments do not reflect the details of the code, so they will not be affected by minor code changes; only changes in overall behavior will affect these comments. Of course, as discussed in Chapter 13, some comments do need to be detailed and precise. But in general, the comments that are most useful (they don’t simply repeat the code) are also easiest to maintain.