IActiveDesigner::QueryPersistenceInterface

Requests information about the persistence interface implemented by the run-time object.

HRESULT QueryPersistenceInterface(
REFIID riid
);

Parameter

riid

[in] Identifier of a persistence interface. Possible values are as follows:

Interface Identifier	Meaning
IID_IPersistFile	File persistence.
IID_IPersistStorage	Storage persistence.
IID_IPersistStream	Stream persistence.
IID_IPersistStreamInit	Stream persistence with initialization.

Return Values

The designer returns one of the following values:

Return Value	Meaning
S_OK	The designer supports the specified persistence interface.
S_FALSE	The designer does not support the specified persistence interface.
E_FAIL	The method failed for an unknown reason.
E_INVALIDARG	The argument is invalid.
E_NOTIMPL	The design-time and run-time objects are the same.
E_OUTOFMEMORY	Not enough memory is available to complete the operation.

Comments

The designer implements this method.

The host uses this method together with the SaveRuntimeState method to save persistent data needed later to create and load the run-time object. It asks the visual designer for persistence interfaces in order of preference.

The persistence interface requested depends on the host; different hosts request different interfaces. Visual Basic versions 5.0 and later, for example, do not use file persistence.

Example

The following example implements QueryPersistenceInterface for an ActiveX designer that supports three persistence interfaces:

STDMETHODIMP CMyDesigner::QueryPersistenceInterface
(
  REFIID riid
)
{
   if (riid == IID_IPersistStreamInit)
     return S_OK;
   else if (riid == IID_IPersistStorage)
     return S_OK;
   else if (riid == IID_IPersistStream)
     return S_OK;
   else 
   return S_FALSE;
}