如何存储单例类的引用？ [英] How to store a reference of a singleton class?

问题描述

我正在开发一个关于经销商向玩家交易卡的项目。

我有单身课经销商和另一个名为 Player 。

I am working on a project relating to a dealer dealing cards to players.
I have the singleton class Dealer and another class called Player.

我已为经销商做了 instance >这部分是我困惑的：

I have made the instance() method for Dealer and this part is where I am confused:

对于单例 Player 类，如何创建一个私有成员名为代理商，其中包含对单身经销商实例的引用？

For the singleton Player class, how do I create a private member called dealer that holds a reference to the singleton Dealer instance?

推荐答案

首先，你应该问自己，如果你真的需要一个单例类来解决这个问题。

In the first place you should ask yourself, if you really need a singleton class to solve this problem at all.

您可以随时将对经销商的实例的引用传递给您的玩家 class：

You can always pass the reference to an instance of Dealer to the constructor of your Player class:

class Player {
public:
    Player(Dealer& dealer_) : dealer(dealer_) {}

private:
    Dealer& dealer;
};

无论如何，它都是在堆栈，堆上或单例实例上构建的。 p>

---

no matter, wether it was constructed on the stack, on the heap or as singleton instance.

对于单例 Player 如何创建私人成员..._

For the singleton Player class, how do I create a private member ..._

常用的c ++ singleton实现模式是

class Dealer{
public:
     static Dealer& instance() {
         static Dealer theDealer;
         return theDealer;
     }

     void foo() {}
private:
     Dealer() {}
     Dealer(const Dealer&) = delete;
     Dealer& operator=(const Dealer&) = delete;
};

注意：您不一定需要存储经销商类，但您可以简单地访问单例实例并调用所需的非静态成员函数

NOTE: You don't necessarily need to store a reference to Dealer class in your client class, but you can simply access the singleton instance and call the desired non static member function

Dealer::instance.foo();

如果你坚持要为单例创建引用成员，你可以：

If you insist to create a reference member to the singleton though, you can do:

class Player {
public:
    Player() : dealer(Dealer::instance()) {}

private:
    Dealer& dealer;
};

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