C++ 宏定义创建（销毁）单例

#define CREATE_SINGLETON_POINTER(CLASS,INSTANCE,MUTEX) if (NULL == INSTANCE) \
                                                    {                                                         MUTEX.lock();                                                         if (NULL == INSTANCE)                                                         {                                                             INSTANCE = new CLASS();                                                         }                                                         MUTEX.unlock();                                                     }

#define DESTORY_SINGLETON_POINTER(INSTANCE) if (NULL != INSTANCE) \
                                            {                                                 delete INSTANCE;                                                 INSTANCE = NULL;                                             }

#include "Foo.h"
#include <mutex>

std::mutex instanceMutex;
Foo* Foo::instance = NULL;
Foo* Foo::getInstance()
{
    CREATE_SINGLETON_POINTER(Foo, instance, instanceMutex);
    return instance;
}

Foo::~Foo()
{
    DESTORY_SINGLETON_POINTER(instance);
}