具有类和结构的命名空间? [英] Namespaces with classes and structs?

问题描述

如果我有D语言的嵌套成员"，那就太好了，所以我有一个聪明的想法去编码

Will be nice if I got 'nested members' in D language, so I have the inglorious idea to code

class Keyboard
{
    struct  Unused {
        string key1 = "Wake Up";
        string key2 = "Sleep";
        string key3 = "Power";
    }

    Unused unused;
}

int main()
{
    Keyboard kb;
    kb.unused.key1 = "Scroll Lock";

    return 0;
}

好的，segfault也是一个不好的例子.但是我正在学习面向对象的编程，不知道这是一件好事还是怎么做.

Okay, it's a bad example that segfault too. But I'm learning object-oriented programming and don't know if it's a good thing to do, or how to do.

推荐答案

本身并没有错，这里的问题是kb仍然是null.您需要创建一个Keyboard对象:

There's nothing wrong with doing that per se, the problem here is that kb is still null. You need to create a Keyboard object:

Keyboard kb = new Keyboard();

如果不想两次键入Keyboard，则可以使用auto:

If you don't want to type Keyboard twice, you can use auto:

auto kb = new Keyboard();

D会自动为您确定正确的类型.

And D will automatically determine the correct type for you.

将相关对象像这样分组在一起是一种相当普遍的做法，尽管通常您会想要一个比Unused更具描述性的名称(否则，为什么要使用命名空间?).

It's fairly common practice to group related objects together like that into a struct, although usually you'll want a more descriptive name than Unused (otherwise, why have the namespace?).

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