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CComClassFactory2 Class

Visual Studio 2012

This class implements the IClassFactory2 interface.

template < 
   class license 
> 
class CComClassFactory2 : public IClassFactory2, 
   public CComObjectRootEx<CComGlobalsThreadModel>, 
   public license

Parameters

license

A class that implements the following static functions:

static BOOL VerifyLicenseKey( BSTR bstr );
static BOOL GetLicenseKey( DWORD dwReserved , BSTR* pBstr );
static BOOL IsLicenseValid( );

Members

Public Methods

Name	Description
CComClassFactory2::CreateInstance	Creates an object of the specified CLSID.
CComClassFactory2::CreateInstanceLic	Given a license key, creates an object of the specified CLSID.
CComClassFactory2::GetLicInfo	Retrieves information describing the licensing capabilities of the class factory.
CComClassFactory2::LockServer	Locks the class factory in memory.
CComClassFactory2::RequestLicKey	Creates and returns a license key.

Remarks

CComClassFactory2 implements the IClassFactory2 interface, which is an extension of IClassFactory. IClassFactory2 controls object creation through a license. A class factory executing on a licensed machine can provide a run-time license key. This license key allows an application to instantiate objects when a full machine license does not exist.

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 CComClassFactory2, specify the DECLARE_CLASSFACTORY2 macro in your object's class definition. For example:

C++

class ATL_NO_VTABLE CMyClass2 :
   public CComObjectRootEx<CComSingleThreadModel>,
   public CComCoClass<CMyClass2, &CLSID_MyClass>,
   public IDispatchImpl<IMyClass, &IID_IMyClass, &LIBID_NVC_ATL_COMLib, /*wMajor =*/ 1, /*wMinor =*/ 0>,
   public IDispatchImpl<IMyDualInterface, &__uuidof(IMyDualInterface), &LIBID_NVC_ATL_COMLib, /* wMajor = */ 1, /* wMinor = */ 0>
{
public:
   DECLARE_CLASSFACTORY2(CMyLicense)

   // Remainder of class declaration omitted

CMyLicense, the template parameter to CComClassFactory2, must implement the static functions VerifyLicenseKey, GetLicenseKey, and IsLicenseValid. The following is an example of a simple license class:

C++

class CMyLicense
{
protected:
   static BOOL VerifyLicenseKey(BSTR bstr)
   {
      USES_CONVERSION;
      return !lstrcmp(OLE2T(bstr), _T("My run-time license key"));
   }

   static BOOL GetLicenseKey(DWORD /*dwReserved*/, BSTR* pBstr) 
   {
      USES_CONVERSION;
      *pBstr = SysAllocString( T2OLE(_T("My run-time license key"))); 
      return TRUE;
   }

   static BOOL IsLicenseValid() {  return TRUE; }
};

CComClassFactory2 derives from both CComClassFactory2Base and license. CComClassFactory2Base, in turn, derives from IClassFactory2 and CComObjectRootEx< CComGlobalsThreadModel >.