6.4 Generality leads to better information hiding 通用性可以更好地隐藏信息

The general-purpose approach provides a cleaner separation between the text and user interface classes, which results in better information hiding. The text class need not be aware of specifics of the user interface, such as how the backspace key is handled; these details are now encapsulated in the user interface class. New user interface features can be added without creating new supporting functions in the text class. The general-purpose interface also reduces cognitive load: a developer working on the user interface only needs to learn a few simple methods, which can be reused for a variety of purposes.

通用方法在文本和用户界面类之间提供了更清晰的分隔，从而可以更好地隐藏信息。文本类不需要知道用户界面的详细信息，例如如何处理退格键。这些细节现在封装在用户界面类中。可以添加新的用户界面功能，而无需在文本类中创建新的支持功能。通用界面还减轻了认知负担：使用用户界面的开发人员只需要学习一些简单的方法，就可以将其重复用于各种目的。

The backspace method in the original version of the text class was a false abstraction. It purported to hide information about which characters are deleted, but the user interface module really needs to know this; user interface developers are likely to read the code of the backspace method in order to confirm its precise behavior. Putting the method in the text class just makes it harder for user interface developers to get the information they need. One of the most important elements of software design is determining who needs to know what, and when. When the details are important, it is better to make them explicit and as obvious as possible, such as the revised implementation of the backspace operation. Hiding this information behind an interface just creates obscurity.

文本类原始版本中的 backspace 方法是错误的抽象。它旨在隐藏有关删除哪些字符的信息，但是用户界面模块确实需要知道这一点。用户界面开发人员可能会阅读退格方法的代码，以确认其精确的行为。将方法放在文本类中只会使用户界面开发人员更难获得所需的信息。软件设计最重要的元素之一就是确定谁需要知道什么以及何时知道。当细节很重要时，最好使它们明确且尽可能明显，例如修订的 Backspace 操作实现。将这些信息隐藏在界面后面只会产生晦涩感。