getInstance（）如何工作？ [英] How does getInstance() work?

问题描述

最近我使用广泛的getInstance（）方法读取了一些C ++代码：

Recent I read some C++ code using extensively following getInstance() method:

class S
{
    private:
        int some_int = 0;
    public:
        static S& getInstance()
        {
            static S instance; / (*) /
            return instance;
        }
};

从这个代码片段的使用方式，我学习了getInstance > return this ，返回类S 的实例的地址（或引用）。但是我感到困惑。

From how this code fragment being used, I learned the getInstance() works like return this, returning the address(or ref) of the instance of class S. But I got confused.

1）在内存中分配的行（*）中定义的静态变量 S ？为什么它可以工作返回这个？

1) where does the static variable S defined in line(*) allocated in memory? And why it can work like return this?

2）如果存在多个<$

2) what if there exist more than one instance of class S, whose reference will be returned?

推荐答案

这是所谓的称为 设计模式。它的区别特征是，只能存在该类的正好一个实例，并且模式确保。该类有一个私有构造函数和一个静态创建的实例，与 getInstance 方法一起返回。

This is the so-called Singleton design pattern. Its distinguishing feature is that there can only ever be exactly one instance of that class and the pattern ensures that. The class has a private constructor and a statically-created instance that is returned with the getInstance method. You cannot create an instance from the outside and thus get the object only through said method.

由于实例是

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