如何在C ++中模拟递归类型定义？ [英] How can I emulate a recursive type definition in C++?

问题描述

昨天我询问了以下问题，为方便起见，转载于此;

Yesterday I asked the following question, reproduced here for convenience;

对于我的一个项目，我真正想做的是这样（简化到最低限度）;

"For one of my projects, what I really wanted to do was this (simplifying it to the bare minimum);

struct Move
{
    int src;
    int dst;
};

struct MoveTree
{
    Move move;
    std::vector<MoveTree> variation;
};

我必须承认，我认为不可能直接做到这一点，我认为一个MoveTree的向量在MoveTree将是verboten，但我尝试了它，它的作品很好，我使用的是Microsoft Visual Studio 2010 Express。

I must admit that I assumed that it wouldn't be possible to do this directly, I thought a vector of MoveTree s within a MoveTree would be verboten. But I tried it anyway, and it works beautifully. I am using Microsoft Visual Studio 2010 Express.

这是可移植的吗？我有什么需要担心的？

Is this portable ? Is it good practice ? Do I have anything to worry about ?"

基本上社区的答案是否定的，我不能这样做安德烈禁止它，所以事实上它的意思是我只是幸运。

Basically the answer from the community was no, I couldn't do this, the standard forbids it, so the fact that it works means I am just getting lucky.

所以我的新问题是。如何在法律C ++中实现我想要的简单功能，而不会增加一堆令人讨厌的复杂性和痛苦？

So my new question is. How can I implement the simple functionality I want in legal C++, without adding a whole heap of nasty complexity and pain ?

推荐答案

你需要使用指针和动态分配。你应该使用智能指针，以确保你不会泄漏任何东西。 boost :: shared_ptr 允许类型不完整，因此这是合法的：

You'll need to use pointers, and dynamic allocation. And you should use smart pointers, to ensure you don't leak anything. boost::shared_ptr allows the type to be incomplete, and therefore this is legal:

std::vector< boost::shared_ptr<MoveTree> > variation;

（我不知道0x std :: shared_ptr TBH，但它应该是一样的）。

(I don't know about 0x std::shared_ptr TBH, but it should be the same).

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