Using GetMem and VarPtr to get around Object default values [duplicate] - excel

Question

This question already has answers here:
How can I assign a Variant to a Variant in VBA?
(5 answers)
Closed 3 years ago.
So I'm making a funky VBA class for callback objects. Currently one of the issues is that when returning data from the function's call method I have to run the method twice, one to determine the variable type and another to return the variable:
If VarType(Application.Run(Callback("Parent") & "." & Callback("Name"), args(0), args(1), args(2), args(3), args(4), args(5), args(6), args(7), args(8), args(9), args(10), args(11), args(12), args(13), args(14), args(15), args(16), args(17), args(18), args(19), args(20), args(21), args(22), args(23), args(24), args(25), args(26), args(27), args(28), args(29))) = vbObject Then
Set CallCallback = Application.Run( _
Callback("Parent") & "." & Callback("Name"), _
args(0), args(1), _
args(2), args(3), _
args(4), args(5), _
args(6), args(7), _
args(8), args(9), _
args(10), args(11), _
args(12), args(13), _
args(14), args(15), _
args(16), args(17), _
args(18), args(19), _
args(20), args(21), _
args(22), args(23), _
args(24), args(25), _
args(26), args(27), _
args(28), args(29))
Else
CallCallback = Application.Run( _
Callback("Parent") & "." & Callback("Name"), _
args(0), args(1), _
args(2), args(3), _
args(4), args(5), _
args(6), args(7), _
args(8), args(9), _
args(10), args(11), _
args(12), args(13), _
args(14), args(15), _
args(16), args(17), _
args(18), args(19), _
args(20), args(21), _
args(22), args(23), _
args(24), args(25), _
args(26), args(27), _
args(28), args(29))
End If
Recently I figured that I might be able to do this without calling the VBA function multiple times by dereferencing the result using VarPtr and then using GetMem4:
Private Declare Function GetMem4 Lib "msvbvm60.dll" (ByVal Addr As Long, ByRef RetVal As Any) As Long
...
Dim vp As LongPtr, vRet as Variant
vp = VarPtr(Application.Run(Callback("Parent") & "." & Callback("Name"), args(0), args(1), args(2), args(3), args(4), args(5), args(6), args(7), args(8), args(9), args(10), args(11), args(12), args(13), args(14), args(15), args(16), args(17), args(18), args(19), args(20), args(21), args(22), args(23), args(24), args(25), args(26), args(27), args(28), args(29)))
Call GetMem4(vp, vRet)
This specific example didn't work but I was wondering whether there was an obvious reason as to why this didn't work?
Any ideas?

Answer 1

I asked the question to vbforums also and they got there much faster than stackoverflow!
The solution is extremely simple:
Public Declare Sub VariantCopy Lib "oleaut32.dll" (ByRef pvargDest As Variant, ByRef pvargSrc As Variant)
...
VariantCopy CallCallback, Application.Run( _
Callback("Parent") & "." & Callback("Name"), _
args(0), args(1), _
args(2), args(3), _
args(4), args(5), _
args(6), args(7), _
args(8), args(9), _
args(10), args(11), _
args(12), args(13), _
args(14), args(15), _
args(16), args(17), _
args(18), args(19), _
args(20), args(21), _
args(22), args(23), _
args(24), args(25), _
args(26), args(27), _
args(28), args(29))
Simple!