弱参照用API

Module1.bas

Option Explicit

Private Type GUID
    Data1 As Long
    Data2 As Integer
    Data3 As Integer
    Data4(0 To 7) As Byte
End Type

Private Declare PtrSafe _
Sub SHWeakReleaseInterface Lib "shlwapi.dll" Alias "#268" ( _
    ByVal arg1 As Any, _
    arg2 As Any _
)

Private Declare PtrSafe _
Function SHWeakQueryInterface Lib "shlwapi.dll" Alias "#267" ( _
    ByVal arg1 As Any, _
    ByVal arg2 As Any, _
    arg3 As GUID, _
    arg4 As Any _
) As Long

Private Declare PtrSafe Sub CopyMemory Lib "kernel32" Alias "RtlMoveMemory" (Destination As Any, Source As Any, ByVal Length As LongPtr)

Sub hoge()

    Dim obj As Object
    Dim tmp As Object
    Dim ptr As Long
    
    Set obj = Application
    ptr = ObjPtr(obj)
    CopyMemory tmp, ptr, 4
    Debug.Print tmp Is Nothing

    'CopyMemory tmp, Nothing, 4
    Call SHWeakReleaseInterface(tmp, tmp)
    Debug.Print tmp Is Nothing

End Sub