August 2021
Intermediate to advanced
450 pages
4h 46m
Chinese
Content preview from 面向对象的思考过程（原书第5版）
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5.6.4 保持尽可能小的作用域
保持类的作用域尽可能小与抽象和隐藏细节息息相关。尽可能地局部化属性和行为。这样维护、测试和扩展类都变得更加容易。使用接口能够进一步增强这样的效果。
作用域和全局数据
最小化全局数据是优秀的编程风格，这并不特定于面向对象编程。全局数据在结构化开发中是允许的，但它们是危险的。事实上，在面向对象开发中没有全局数据。静态属性和方法只在同一个类的对象间共享，然而对于其他类的对象则是不可见的。你也能够通过文件和数据库来共享数据。
例如，如果你有一个方法要求一个临时变量，请保持该变量本地化。请看以下代码：
该类有什么问题？问题在于只在swap()方法的作用域内需要temp属性。没有理由将temp属性放置到类级别。因此，你应该把temp移动到swap()方法的作用域中：
这就是为什么要保持尽可能小的作用域。
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