如何使用CComCoClass创建单例 [英] How to use CComCoClass to create a singleton

问题描述

我在我的类中使用DECLARE_CLASSFACTORY_SINGLETON，但CComCoClass :: CreateInstance仍会在每次调用时返回一个新实例。但是，CComCoClass :: CreateInstance的文档明确指出：" COM对象
的创建由为此ATL类注册的类工厂执行。 （ https://docs.microsoft.com/en-us/cpp/atl/reference/ccomcoclass-class#createinstance ）

I use DECLARE_CLASSFACTORY_SINGLETON in my class, but CComCoClass::CreateInstance still returns a new instance on each call. However, the documentation for CComCoClass::CreateInstance explicitly states: "The creation of the COM object is carried out by the class factory registered for this ATL class." (https://docs.microsoft.com/en-us/cpp/atl/reference/ccomcoclass-class#createinstance)

这是文档或实现中的错误吗？

Is this a bug in the documentation or implementation?

注意：在相关帖子中（https：//social.msdn。 microsoft.com/Forums/en-US/fb904036-6e5e-4953-8865-e6e7fda4e550/how-to-make-ccomcoclass-singleton?forum=vcgeneral)the"solution""只是调用CoCreateInstance，这确实可以正常工作。

Note: In a related post (https://social.msdn.microsoft.com/Forums/en-US/fb904036-6e5e-4953-8865-e6e7fda4e550/how-to-make-ccomcoclass-singleton?forum=vcgeneral) the "solution" is to just call CoCreateInstance, and this indeed does work as intended.

推荐答案

你好zvrba，

Hi zvrba,

感谢您在此处发帖。

>>我在我的课程中使用DECLARE_CLASSFACTORY_SINGLETON，但CComCoClass :: CreateInstance仍然返回每次通话都有一个新实例。但是，CComCoClass :: CreateInstance的文档明确指出：" COM对象的创建
由为此ATL类注册的类工厂执行。" （ 的 https://docs.microsoft.com/en-us/cpp/atl/reference/ccomcoclass-class#createinstance <跨度>的）

>>I use DECLARE_CLASSFACTORY_SINGLETON in my class, but CComCoClass::CreateInstance still returns a new instance on each call. However, the documentation for CComCoClass::CreateInstance explicitly states: "The creation of the COM object is carried out by the class factory registered for this ATL class." (https://docs.microsoft.com/en-us/cpp/atl/reference/ccomcoclass-class#createinstance)

DECLARE_CLASSFACTORY_SINGLETON宏用于将CComClassFactorySingleton声明为类工厂。要使用CComClassFactorySingleton，请在对象的类定义中指定DECLARE_CLASSFACTORY_SINGLETON宏。例如：

The DECLARE_CLASSFACTORY_SINGLETON macro is used to declare CComClassFactorySingleton to be the class factory. To use CComClassFactorySingleton, specify the DECLARE_CLASSFACTORY_SINGLETON macro in your object's class definition. For example:

class ATL_NO_VTABLE CMySingletonClass :
   public CComObjectRootEx<CComSingleThreadModel>,
   public CComCoClass<CMySingletonClass, &CLSID_MySingletonClass>,
   public IMySingletonClass
{
public:
   DECLARE_CLASSFACTORY_SINGLETON(CMySingletonClass)

然后你可以调用
CComClassFactorySingleton :: CreateInstance 以检索接口指针。

Then you could call CComClassFactorySingleton::CreateInstance to retrieve an interface pointer.

>>在相关帖子中（https://social.msdn.microsoft.com/Forums/en-US/fb904036-6e5e-4953-8865-e6e7fda4e550/how-to-make-ccomcoclass- singleton？forum = vcgeneral）"解决方案"只是打电话给CoCreateInstance，这确实按预期工作
。

如果你仔细阅读案例，你会发现答案是停止使用CComObject :: CreateInstance。

If you read the case carefully, you will find the the answer is to stop using CComObject::CreateInstance.

希望这可以帮到你。

最好的问候，

Baron Bi

Baron Bi

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