| description | title | ms.date | f1_keywords | helpviewer_keywords | ms.assetid | |||||
|---|---|---|---|---|---|---|---|---|---|---|
Learn more about: CComClassFactorySingleton Class |
CComClassFactorySingleton Class |
11/04/2016 |
|
|
debb983c-382b-487b-8d42-7ea26dc158b8 |
This class derives from CComClassFactory and uses CComObjectGlobal to construct a single object.
Important
This class and its members cannot be used in applications that execute in the Windows Runtime.
template<class T>
class CComClassFactorySingleton : public CComClassFactory
T
Your class.
CComClassFactorySingleton derives from CComClassFactory and uses CComObjectGlobal to construct a single object. Each call to the CreateInstance method simply queries this object for an interface pointer.
| Name | Description |
|---|---|
| CComClassFactorySingleton::CreateInstance | Queries m_spObj for an interface pointer. |
| Name | Description |
|---|---|
| CComClassFactorySingleton::m_spObj | The CComObjectGlobal object constructed by CComClassFactorySingleton. |
ATL objects normally acquire a class factory by deriving from CComCoClass. This class includes the macro DECLARE_CLASSFACTORY, which declares CComClassFactory as the default class factory. To use CComClassFactorySingleton, specify the DECLARE_CLASSFACTORY_SINGLETON macro in your object's class definition. For example:
[!code-cppNVC_ATL_COM#10]
CComObjectRootBase
IClassFactory
CComClassFactorySingleton
Header: atlcom.h
Calls QueryInterface through m_spObj to retrieve an interface pointer.
STDMETHOD(CreateInstance)(LPUNKNOWN pUnkOuter, REFIID riid, void** ppvObj);
pUnkOuter
[in] If the object is being created as part of an aggregate, then pUnkOuter must be the outer unknown. Otherwise, pUnkOuter must be NULL.
riid
[in] The IID of the requested interface. If pUnkOuter is non- NULL, riid must be IID_IUnknown.
ppvObj
[out] A pointer to the interface pointer identified by riid. If the object does not support this interface, ppvObj is set to NULL.
A standard HRESULT value.
The CComObjectGlobal object constructed by CComClassFactorySingleton.
CComPtr<IUnknown> m_spObj;
Each call to the CreateInstance method simply queries this object for an interface pointer.
Note that the current form of m_spObj presents a breaking change from the way that CComClassFactorySingleton worked in previous versions of ATL. In previous versions the CComClassFactorySingleton object was created at the same time as the class factory, during server initialization. In Visual C++.NET 2003 and later, the object is created lazily, on the first request. This change could cause errors in programs that rely on early initialization.
IClassFactory
CComClassFactory2 Class
CComClassFactoryAutoThread Class
CComObjectRootEx Class
CComGlobalsThreadModel
Class Overview