Question

For debugging reasons I want to destroy a class instance which still as references. Is that possible? It doesn’t have to be elegant or stable, because this’ll never end up in production code.

To clarify:

Public Sub Main
    Dim o as MyClass
    Set o = New MyClass //o is created, one reference
    DestroyObject o     //Class_Terminate is called and the object destroyed
    //Further code, not using o
End Sub                 //Possible runtime error here (don't care)

Is that possible? One way would be to call IUnknown::Release to manually decrease the reference count, but how do I now how often I must call it?

Answer 1

This is a very bad idea

Option Explicit

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

Private m_oRef As Class1

Private Sub Command1_Click()
    Dim o As Class1

    Set o = New Class1
    Set m_oRef = o
    DestroyObject o
    ' releasing m_oRef after this point will bring down the IDE '
End Sub

Private Sub DestroyObject(pArg As Object)
    Dim lRefCount       As Long
    Dim lIdx            As Long
    Dim pUnk            As IUnknown

    lIdx = ObjPtr(pArg) + &H20
    Call CopyMemory(lRefCount, ByVal lIdx, 4)
    For lIdx = 1 To lRefCount - 2
        Call CopyMemory(pUnk, pArg, 4)
        Set pUnk = Nothing
    Next
    Set pArg = Nothing
End Sub