How to debug Reference Count of VB ActiveX Control?

Leo

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Dec 4, 2000, 3:00:00 AM12/4/00

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Visual Basic 6.0
As title.
Thanks for any suggestion.

Phil Jollans

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Dec 4, 2000, 3:00:00 AM12/4/00

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This would interest me too, but I don't believe that there is any way to do
it!

Alexander Milenz

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Dec 4, 2000, 3:00:00 AM12/4/00

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This Code will get you the Reference Count. You may even call IUnknown's
AddRef & Release methods, though I would advise against doing this until you
know PRECISELY what you are doing. Simply put this into any module and let
your Control update it's Title with the value.

----------------------------------------------------------------------------
----

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

Public Function RefCount(ByVal unk As IUnknown) As Long
Dim RefCountAddr As Long
Dim RefCounter As Long

RefCountAddr = ObjPtr(unk) + 4
If RefCountAddr = 4 Then
RefCount = 0
Exit Function
End If
ICopyMemory RefCounter, ByVal RefCountAddr, 4
RefCount = RefCounter - 2
End Function

Public Sub AddRef(ByVal unk As IUnknown)
Dim RefCountAddr As Long
Dim RefCounter As Long

RefCountAddr = ObjPtr(unk) + 4
If RefCountAddr = 4 Then
RefCount = 0
Exit Function
End If
ICopyMemory RefCounter, ByVal RefCountAddr, 4
RefCounter = RefCounter + 1
ICopyMemory ByVal RefCountAddr, RefCounter, 4
End Sub

Public Sub Release(ByVal unk As IUnknown)
Dim RefCountAddr As Long
Dim RefCounter As Long

RefCountAddr = ObjPtr(unk) + 4
If RefCountAddr = 4 Then
RefCount = 0
Exit Function
End If
ICopyMemory RefCounter, ByVal RefCountAddr, 4
RefCounter = RefCounter - 1
ICopyMemory ByVal RefCountAddr, RefCounter, 4
End Sub
----------------------------------------------------------------------------
----------------------------

I know this works for VB Classes, and it *should* work for controls as well,
though I never tested it.
If you are intersted in doing some nasty things with VB then go and read:
>> Dan Appleman's developing COM Components with Visual Basic 6.0: A Guide
to the perplexed<<

Hope this helps
Alexander Milenz

"Phil Jollans" <Phil.J...@messring.de> schrieb im Newsbeitrag
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Leo

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Dec 4, 2000, 10:05:13 PM12/4/00

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Thank you very much, Alexander.
I want to trace the reference count when AddRef or Release method of control
was called.
That is mean I want to "hook" the two method with my implement.
That is mean I want to "overload" the two method with my implement.
Only in this way, I can output debug string in my implement.
The effect is:
Class A:
Public Sub AddRef()
Debug.Print "Reference Count is " & GetRefCount()
call OldAddRef()
End Sub
How can I "overload"?
Thanks for any suggestion.

"Alexander Milenz" <Ras...@bigfoot.com> wrote in message
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Alexander Milenz

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Dec 8, 2000, 3:00:00 AM12/8/00

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Honestly, I don't know exactly how overloading is done in VB.
Implement does NOT do the job. You have to copy some function tables in the
memory.
(and there comes you personal GPF)

> If you are intersted in doing some nasty things with VB then go and read:
> >> Dan Appleman's developing COM Components with Visual Basic 6.0: A Guide
> to the perplexed<<

I know that Appleman explains the technique quite well in his book, so all I
can suggest
is: go and read that book - it's worth it.

Alex

"Leo" <nk...@263.net> schrieb im Newsbeitrag
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