什么是动态转换的“好用"示例?

What are some #39;good use#39; examples of dynamic casting?(什么是动态转换的“好用示例?)

问题描述

我们经常听到/读到应该避免动态转换.我想知道根据你的说法，什么是它的好用"示例?

We often hear/read that one should avoid dynamic casting. I was wondering what would be 'good use' examples of it, according to you?

是的，我知道其他线程:它是确实在阅读我提出问题的第一个答案时！

Yes, I'm aware of that other thread: it is indeed when reading one of the first answers there that I asked my question!

推荐答案

这个最近的主题给出了一个它可以派上用场的例子.有一个基本的 Shape 类和从它派生的类 Circle 和 Rectangle .在测试相等性时，很明显圆形不能等于矩形，尝试比较它们将是一场灾难.在遍历指向 Shapes 的指针集合时，dynamic_cast 执行双重任务，告诉您这些形状是否具有可比性，并为您提供合适的对象来进行比较.

This recent thread gives an example of where it comes in handy. There is a base Shape class and classes Circle and Rectangle derived from it. In testing for equality, it is obvious that a Circle cannot be equal to a Rectangle and it would be a disaster to try to compare them. While iterating through a collection of pointers to Shapes, dynamic_cast does double duty, telling you if the shapes are comparable and giving you the proper objects to do the comparison on.

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