面向对象编程-类设计的困惑 [英] Object oriented programming - class design confusion

问题描述

我正在努力将注意力集中在面向对象的编程上.

I am trying to wrap my head around object oriented programming.

我的理解是我们有对象，因此我们可以设计程序来镜像现实生活中的对象.

My understanding is that we have objects so we can design our programs to mirror real-life objects.

让我们看一个类层次结构:

Let's take a class hierarchy:

class Fruit {
    void Eat() {

    }
}

class Apple extends Fruit {

}

很明显，如果Eat()是虚拟的，则可以多态使用Fruit.但这有道理吗?水果不能吃东西！

Obviously, you can use Fruit polymorphically if Eat() is virtual. But does this make sense? Fruit cannot eat itself!

应该将水果对象传递给具有Eat()功能的人类对象吗?

Should a fruit object rather be passed to a human object which has a Eat() function?

我正在尝试找出思考此问题的正确方法.通常，编程对象应与现实生活的对象保持多近的距离?

I am trying to figure out the correct way to think about this. How closely, in general, should programming objects mirror real-life objects?

推荐答案

您遇到了一个设计问题-正如您正确指出的那样，Eat()作为Fruit成员的意义不大.另一方面，可食用的" 属性会更有意义.就像"onEaten"事件 一样，您的水果/苹果类所暴露的内容(以及模型中其他有意义的对象)取决于很多其他因素，包括您要尝试的因素.在您的应用程序中完成这些构造.

You've got a design problem -- as you correctly point out, Eat() doesn't make obvious sense as a member of Fruit. On the other hand, an "edible" attribute would make more sense. As would an "onEaten" event, etc. What your fruit/apple classes expose (and what other objects make sense in your model) depends on a lot of other factors, including what you're trying to accomplish with those constructs in your application.

通常，您希望您的类表示逻辑域级别的实体.有时，它们对应于现实世界中的物理实体，但在许多情况下却不对应.

In general you want your classes to represent logical domain level entities. Sometimes those correspond to a physical entity in the real world, but in many cases they don't.

在我看来，OO问题分解是程序员通常不擅长的事情.我不知道我有多少次看到过类似方向盘衍生的汽车并摇了摇头，而原始的开发人员却无法解决他们的设计为什么意义不大的问题.

In my opinion OO problem decomposition is something programmers are generally pretty bad at. I don't know how many times I've seen the equivalent of a car derived from a steering wheel and shaken my head while the original developer couldn't wrap their head around why their design didn't make a lot of sense.

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