IPersist::GetClassID
Returns the class identifier (CLSID) the component object. The CLSID is a
unique value that identifies the application that can manipulate the component
object data.
HRESULT GetClassID(
CLSID *pClassID
| //Pointer to CLSID of component object
|
);
|
|
Parameter
pClassID
[out]Points to the location where the CLSID is returned. The CLSID is a
globally unique identifier (GUID) that uniquely represents an object class.
Return Values
S_OK
The CLSID was successfully returned.
E_FAIL
The CLSID could not be returned.
Comments
This method returns the class identifier (CLSID) for an object, used in later
operations to load object-specific code into the caller's context.
Notes to Callers
Most container applications have no need to call the
IPersist::GetClassID method directly. A container application might use this method when the
container needs to change the CLSID and save the new CLSID for the component object.
For example, if the container is treating a component as a different class and
an editing operation occurs so that the component object can no longer be
edited by its original application. In this case, the container needs to change the
CLSID for the component. Typically, in this case, the container calls the
OleSave helper function which performs all the necessary steps.
The exception would be a container that provides an object handler for certain
component objects. In particular, a container application should not get a
component object CLSID and then use it to retrieve class specific information from
the registry. Instead, the container should use
IOleObject and
IDataObject interfaces to retrieve such class-specific information directly from the
object.
Notes to Implementors
Typically, a component object simply returns a constant CLSID in its
implementation of this method. This is not the case, however, if your component object
supports "Treat As" operations in which it edits other classes of components as
if they were its own class. If your object is running a component of another
class, your implementation of
IPersist::GetClassID must return the CLSID stored in the component storage.
The implementation of
IPersist::GetClassID in the default object handler passes the call to the implementation in the
component object if the component object is running. Otherwise, the default
handler calls the
ReadClassStg function to read the CLSID that is saved in the component object storage.
If you are writing a custom object handler for your component, you might want
to simply delegate this method to the default handler implementation (see
OleCreateDefaultHandler).
See Also
IDataObject::EnumFormatEtc,
IOleObject::EnumVerbs,
IOleObject::GetMiscStatus,
IOleObject::GetUserType,
OleCreateDefaultHandler,
ReadClassStg
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