10.10 Taking it too far 走得太远

Defining away exceptions, or masking them inside a module, only makes sense if the exception information isn’t needed outside the module. This was true for the examples in this chapter, such the Tcl unset command and the Java substring method; in the rare situations where a caller cares about the special cases detected by the exceptions, there are other ways for it to get this information.

定义异常或将其屏蔽在模块内部，仅在模块外部不需要异常信息时才有意义。对于本章中的示例，例如 Tcl unset 命令和 Java 子字符串方法，都是如此。在极少数情况下，呼叫者关心异常检测到的特殊情况，还有其他方法可以获取此信息。

However, it is possible to take this idea too far. In a module for network communication, a student team masked all network exceptions: if a network error occurred, the module caught it, discarded it, and continued as if there were no problem. This meant that applications using the module had no way to find out if messages were lost or a peer server failed; without this information, it was impossible to build robust applications. In this case, it is essential for the module to expose the exceptions, even though they add complexity to the module’s interface.

但是，有可能使这个想法太过分。在用于网络通信的模块中，一个学生团队掩盖了所有网络异常：如果发生网络错误，则模块将其捕获，丢弃并继续进行，就好像没有问题一样。这意味着使用该模块的应用程序无法确定消息是否丢失或对等服务器是否发生故障；没有这些信息，就不可能构建健壮的应用程序。在这种情况下，模块必须公开异常，即使它们增加了模块接口的复杂性。

With exceptions, as with many other areas in software design, you must determine what is important and what is not important. Things that are not important should be hidden, and the more of them the better. But when something is important, it must be exposed.

与软件设计中的许多其他领域一样，您必须确定哪些是重要的，哪些是不重要的。不重要的事物应该被隐藏起来，它们越多越好。但是，当某件事很重要时，必须将其暴露出来。