[VB6] Call Functions By Pointer (Universall DLL Calls)

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Originally Posted by wqweto

The same global object problem exists with standard Scripting.Dictionary -- just don't keep instances of these STA components in IIS application state but use IISSample.LookupTable replacement which is a free-threaded component AFAIK.

cheers,
</wqw>

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Brill, thanks mate. I'll look into the IISSample.LookupTable.

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Originally Posted by jsvenu

Dear Lavolpe,

I tried to hide form 2 in standard exe project.It hides if I use tc.hide directly where tc is form2 object.
But when I try to hide form2 using CallFunction_COM giving 516 as the address of Hide method
'ie, vtableoffset as per interface _Form which derives from IDispatch located in vb6.olb in vb98 folderwhen we view the typelib using oleview.Hide is the 122th method+3(for IUnknown)+4(for IDispatch)=129*4bytes=516.
the Hide method of the form2 is not called.
Can you clarify me where I am doing wrong.
I am attaching the sample standard exe project.I have used your cUniversalDLLCalls class from prjUniDLLcalls.zip sample.

regards,
jsvenu

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Code:

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        sName = "Hide" ' << change to another known method in the class

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does it can get more disp id?

Code:

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        Dim vv(2) As Long
        Dim lDispIDList(2) As Long
        Dim S(2) As String
        S(0) = "Caption"
        S(1) = "aa"
        S(2) = "Hide"
        vv(0) = StrPtr(S(0))
        vv(1) = StrPtr(S(1))
        vv(2) = StrPtr(S(2))
   
        Call c.CallFunction_COM(IID_Dispatch, IDispatchIDsOfNames, CR_LONG, CC_STDCALL, VarPtr(aGUID(0)), VarPtr(vv(0)), 1&, 0&, VarPtr(lDispIDList(0)))

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i only use this code can hide form2,but pIndex = DispCallFunc(*)<>0 why?
i do GetLastDllErr

do you have a full sample?

The second similar question, is it possible to write the event callback on the VB6 class object, implement the IUnknown interface, and delete all the redundant interfaces in the class?
This way I don't have to create a module with each callback and implement the virtual IUnknown interface.

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Originally Posted by LaVolpe

Bonnie, if this is a Sub from a VB class you want to call, and you know the method's name, far easier:
:: Copy pointer to uninitialized object and call the Object.SubName, remove pointer from that object, done

1) declare a variable vArgs() As Variant, size it to the number of parameters the method expects
2) populate it in reverse order and ensure the correct vartype of each param, example:
[indent]method's params: (Index As Integer, NewValue As Long)

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Code:

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Function CallComByMethod(Obj1 As Object, MethodName As String, ParamArray ArgP() As Variant) As Variant
  Const IUnknownRelease As Long = 8&
    Const IDispatchIDsOfNames As Long = 20&
    Const IDispatchInvoke As Long = 24&
   
    Dim IID_Dispatch As Long, lDispID As Long
    Dim aGUID(0 To 3) As Long, sName As String
    Dim DP As DISPPARAMS, vRtn As Variant
    Dim C As New cUniversalDLLCalls
 
   
    sName = "{00020400-0000-0000-C000-000000000046}" ' GUID for IDispatch
    C.CallFunction_DLL "ole32.dll", "IIDFromString", STR_NONE, CR_LONG, CC_STDCALL, StrPtr(sName), VarPtr(aGUID(0))
    ' ensure object implements IDispatch...
    C.CallFunction_COM ObjPtr(Obj1), 0&, CR_LONG, CC_STDCALL, VarPtr(aGUID(0)), VarPtr(IID_Dispatch)
    If IID_Dispatch <> 0& Then
        Erase aGUID()
        Call C.CallFunction_COM(IID_Dispatch, IDispatchIDsOfNames, CR_LONG, CC_STDCALL, VarPtr(aGUID(0)), VarPtr(MethodName), 1&, 0&, VarPtr(lDispID))
        If lDispID > 0 Then
        Dim Arg() As Variant
        Dim i As Long, ub As Long
        ub = UBound(ArgP)
       
        If ub <> -1 Then
        ReDim Arg(ub)
        For i = 0 To ub
            '以相反的顺序填充它并确保每个参数的正确 vartype
            Arg(i) = ArgP(ub - i)
            'Arg(i) = VarPtr(ArgP(ub - i))
        Next
        DP.rgVarg = VarPtr(ArgP(0))
        'DP.rgVarg = VarPtr(Arg(0))
        DP.cArgs = ub + 1
        End If
            Call C.CallFunction_COM(IID_Dispatch, IDispatchInvoke, CR_LONG, CC_STDCALL, lDispID, VarPtr(aGUID(0)), 0&, 1&, VarPtr(DP), VarPtr(vRtn), 0&, 0&)
            Debug.Print "return value if any: "; vRtn
            CallComByMethod = vRtn
        Else
            Debug.Print "method ["; sName; "] not found"
        End If
        ' Release the interface at some point. QueryInterface calls AddRef internally
        C.CallFunction_COM IID_Dispatch, IUnknownRelease, CR_LONG, CC_STDCALL
    End If
End Function

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, ParamArray ArgP() As Variant
How about reversing the order of the parameters, because my parameters also return values, so I can't create a variant copy.