Properties with Optional Parameters Not Supported

This article was previously published under Q131048

Properties with optional parameters are currently not supported by the IDispatch::Invoke implementation provided by the OLE system (DispInvoke and CreateStdDispatch). For example, the following results in an error from MKTYPLIB.EXE:

[propput]
void MyProperty([in] BSTR bstrValue, [in, optional] VARIANT vIndex,);
[propget]
BSTR MyProperty([in, optional] VARIANT vIndex);
		

Properties with non-optional parameters are allowed. For example, the following is acceptable:

[propput] void MyProperty([in] short nIndex, [in] BSTR bstrValue);
[propget] BSTR MyProperty([in] short nIndex);