Trying to reverse ObjPtr to an Object I'm getting kernel not found error 53 in 64 bits but not in 32 bits

问题

I'm referring Parent class from Child class; instead of simply do, for example:

Public Property Set Parent(obj As ClassProperties)
    Set this.ParentColl = obj
End Property

I rather prefer to avoid references to and from getting entangled and 'out of memory' error when I loop through and create instances of the class so I use this that is based on that.

It functions as a charm in 32 bits but at 64 bits I'm getting Runtime error '53' File not found: kernel.

In a module:

#If VBA7 Then
    Private Declare PtrSafe Sub CopyMemory Lib "kernel" Alias "RtlMoveMemory" _
     (dest As Any, Source As Any, ByVal Length As LongPtr)
#Else
    Private Declare Sub CopyMemory Lib "kernel32" Alias "RtlMoveMemory" _
     (dest As Any, Source As Any, ByVal Length As Long)
#End If

'Returns an object given its pointer.
Public Function ObjFromPtr(ByVal pObj As Long) As Object
    Dim obj As Object
    CopyMemory obj, pObj, 4
    Set ObjFromPtr = obj
    CopyMemory obj, 0&, 4
End Function

Public Function ObjFromPtrVBA7(ByVal pObj As LongPtr) As Object
    Dim obj As Object
    CopyMemory obj, pObj, 4  <== here is the error
    Set ObjFromPtrVBA7 = obj
    CopyMemory obj, 0&, 4
End Function

At Child class:

    #If VBA7 Then 'Uses modParentChildDereference
    Private mlParentPtr As LongPtr
    #Else
    Private mlParentPtr As Long
    #End If
Public Property Get Parent() As ClassProperties 
    #If VBA7 Then 'Uses modParentChildDereference
    Set Parent = modParentChildDereference.ObjFromPtrVBA7(mlParentPtr)
    #Else
    Set Parent = modParentChildDereference.ObjFromPtr(mlParentPtr)
    #End If
End Property
Public Property Set Parent(obj As ClassProperties)
    mlParentPtr = ObjPtr(obj)
End Property

At Parent Class:

    Set newItem.Parent = Me

At CopyMemory obj, pObj, 4 I can see the LongPtr, like 1234567789^, but CopyMemory is unable to find the Obj at kernel.

I read some deep threads over CopyMemory here and here.

Based on those I played a little with CopyMemory obj, pObj, 4 and gave it different numbers, like 8 and 16 but to no avail.

Any directions or solutions? TIA

回答1:

The link provided by @UnhandledException in the comment above directed me to an amazing thread

I implemented it, adapting to 64 bits - see my answer there - and got a totally different kind of errors, even crashing VBE, video driver and windows.

But one comment at OP opened my eyes:

Please don't hard-code the size... ever. LenB is to VBA what sizeof is to C. Use it to size the allocation for the copy memory API. – this

Back to work:

Public Function ObjFromPtr(ByVal pObj As Long) As Object
    Dim obj As Object
    CopyMemory obj, pObj, LenB(obj) 'not size 4!
    Set ObjFromPtr = obj
    CopyMemory obj, 0&, LenB(obj) 'not size 4!
End Function

Public Function ObjFromPtrVBA7(ByVal pObj As LongPtr) As Object
    Dim obj As Object
    CopyMemory obj, pObj, LenB(obj) 'not size 4!  <== here the error no more!!!!
    Set ObjFromPtrVBA7 = obj
    CopyMemory obj, 0&, LenB(obj) 'not size 4!
End Function

So, answered.

Thanks a lot community!

来源：https://stackoverflow.com/questions/60943510/trying-to-reverse-objptr-to-an-object-im-getting-kernel-not-found-error-53-in-6

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