正确删除单例 [英] Properly deleting a singleton

问题描述

我有以下代码：

MyClass.h：

MyClass.h:

static MyMutex instanceMutex;
static MyClass* getInstance();
static void deleteInstance();

MyClass.c：

MyClass.c:

MyMutex MyClass::instanceMutex;

MyClass* MyClass::getInstance()
{   
    if (theInstance == 0)
    {
        instanceMutex.acquire();
        if (theInstance == 0)
        {
            theInstance  = new MyClass();
        }
        instanceMutex.release();
    }
    return theInstance;
}

void MyClass::deleteInstance()
{   
    if (theInstance != 0)
    {
        instanceMutex.acquire();
        if (theInstance != 0)
        {
           theInstance->finalize();
           delete theInstance; 
           theInstance = 0;
        }
        instanceMutex.release();
    }
    return;
}

我有两个问题：

在MyClass :: deleteInstance（）中调用delete theInstance之后，然后我调用

• Is the above code correct and safe?

• After I call 'delete theInstance' in MyClass::deleteInstance(), I then call

• theInstance = 0;


• instanceMutex.release（）;

但是如果实例被删除，那么怎么可能呢？

But if the instance is deleted than how is that even possible? isn't the memory of the class gone?

推荐答案

singleton - 它被定义为只有一个实例 - 如果你删除它 - 这降到0

If it's a singleton - it is defined to have exactly one instance - if you delete it - this drops to 0

所以看来你不应该支持删除

So it seems you should not support delete at all

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