OLECLSID type

A class or interface identifier, with the layout of the Windows GUID structure.

OLECLSID is a user-defined type declared in the package’s OLEGuids module, so both OLECLSID and OLEGuids.OLECLSID name it. It mirrors the Windows structure GUID, which the interface declarations use for a class identifier (CLSID) and for an interface identifier (IID) alike.

Public Type OLECLSID
    Data1 As Long
    Data2 As Integer
    Data3 As Integer
    Data4(0 To 7) As Byte
End Type

Fields

Data1

A Long holding the first eight hexadecimal digits of the identifier. The Windows field is unsigned, so a value above &H7FFFFFFF appears negative.

Data2

An Integer holding the next four digits.

Data3

An Integer holding the next four digits.

Data4

An array of eight Byte values, indexed from 0 to 7, holding the last sixteen hexadecimal digits, two to a byte.

For the identifier 00020400-0000-0000-C000-000000000046, Data1 is &H00020400, Data2 and Data3 are 0, and Data4 holds &HC0, 0, 0, 0, 0, 0, 0 and &H46.

An OLECLSID variable that is not filled in holds only zeros, which is the null identifier IID_NULL that IDispatch.GetIDsOfNames and IDispatch.Invoke ask for in their riid parameter.

Where it is used

• IDispatch.GetIDsOfNames and IDispatch.Invoke – riid, by reference.
• IObjectSafety.GetInterfaceSafetyOptions and SetInterfaceSafetyOptions – riid, by reference.
• IPerPropertyBrowsing.MapPropertyToPage – pCLSID, by reference.
• IRichEditOle.ConvertObject – pCLSIDNew, and IRichEditOle.ActivateAs – pCLSID and pCLSIDAs, by reference.
• IRichEditOleCallback.QueryInsertObject – pCLSID, by reference.
• IUnknownUnrestricted.QueryInterface – priid is the address of the identifier, from VarPtr.

Example

This procedure asks an object which safety options it supports for the IDispatch interface. The identifier 00020400-0000-0000-C000-000000000046 is written into an OLECLSID field by field.

Private Function DispatchSafetyOptions(ByVal Obj As IObjectSafety) As Long
    Dim iid As OLECLSID
    iid.Data1 = &H20400
    iid.Data4(0) = &HC0
    iid.Data4(7) = &H46

    Dim supported As Long
    Dim enabled As Long
    Obj.GetInterfaceSafetyOptions iid, supported, enabled
    Return supported
End Function

See Also

• IDispatch interface – finds and calls members of an automation object
• IObjectSafety interface – reports and sets an object’s safety options
• OLECAUUID type – a counted array of GUIDs