C++ 写单例的办法

先在头文件声明：

声明一个COemInstancer的 _this指针：

static COemInstance* _this;

.然后在文件外层这样写：

#define CXXModule COemInstance::instance()

#define ExecuteCommand(ClassName,RunCommand) class Tempclass##ClassName\
{public:Tempclass##ClassName(){RunCommand;}};\
 Tempclass##ClassName g_Tempclass##ClassName;

cpp:这样写：

先全局声明：

COemInstance * COemInstance::_this = nullptr;

ExecuteCommand(COemInstance, COemInstance::instance())

调用的时候就可以

 CXXModule--->xxx

多一层ExecuteCommand 的好处是确保百分百加载，然后在多线程中确保安全加载

COemInstance* COemInstance::instance()
{
    if (!_this)
    {
        if (!_bDestoryed_)
        {
            _this = new COemInstance();
            //_this->Initialization();
            atexit(&COemInstance::destory);
        }
    }
    return _this;
}

void COemInstance::destory()
{
    if (_this)
    {
        delete _this;
        _this = NULL;
        _bDestoryed_ = true;
    }
}