IDispatch expose methods to other languages

[Cliff Nichols]

Thomas,
Let me see if I can work one up. I can easily use a COM that already exists, but creating a COM from scratch that seems to be where I am taking a hit

It is probably the VB background I have and trying to not make it worse for the "Non-Programmers" I know will follow, but I am trying.

[Thomas Tierney]

Cliff,

I have been able to get Native PB Com methods called from JSCRIPT, VBSCRIPT and Visual Basic with out any problems. Do you have sample code which reproduces the error?

[Steven Pringels 3]

You'll need this as well.

' ****************************************************************************************
' Maps a single member to a corresponding DispID, which can be used on subsequent calls to
' IDispatch_Invoke.
' ****************************************************************************************
DECLARE FUNCTION Proto_IDispatch_GetIDOfName (BYVAL pthis AS DWORD PTR, BYREF riid AS GUID, BYREF rgszNames AS STRING, BYVAL cNames AS DWORD, BYVAL lcid AS DWORD, BYREF rgdispid AS LONG) AS LONG
' ****************************************************************************************
FUNCTION IDispatch_GetIDOfName (BYVAL pthis AS DWORD PTR, BYREF strName AS STRING, BYREF rgdispid AS LONG) AS LONG
    LOCAL HRESULT AS LONG, riid AS GUID
    IF pthis = %NULL THEN FUNCTION = %E_POINTER : EXIT FUNCTION
    CALL DWORD @@pthis[5] USING Proto_IDispatch_GetIDOfName (pthis, riid, strName, 1, 0, rgdispid) TO HRESULT
    FUNCTION = HRESULT
END FUNCTION
' ****************************************************************************************

' ****************************************************************************************
' Provides access to properties and methods exposed by an object.
' Note: if the call to Invoke returns %DISP_E_EXCEPTION (&H80020009), the EXCEPINFO
' structure is filled with error information. Three of his members are pointers to
' unicode strings that you can read with the TB_ExcepInfoErrorDescription,
' TB_ExcepInfoErrorSource and TB_ExcepInfoErrorHelpFile functions, and that you must free
' with SysFreeString: SysFreeString pexcepinfo.bstrDescription,
' SysFreeString pexcepinfo.bstrSource, SysFreeString pexcepinfo.bstrHelpFile.
' ****************************************************************************************
FUNCTION IDispatch_Invoke (BYVAL pthis AS DWORD PTR, BYVAL dispidMember AS LONG, BYREF riid AS GUID, _
    BYVAL lcid AS DWORD, BYVAL wFlags AS WORD, BYREF pdispparams AS DISPPARAMS, BYREF pvarResult AS VARIANT, _
    BYREF pexcepinfo AS EXCEPINFO, BYREF puArgErr AS DWORD) AS LONG
    LOCAL HRESULT AS LONG
    IF pthis = %NULL THEN FUNCTION = %E_POINTER : EXIT FUNCTION
    CALL DWORD @@pthis[6] USING IDispatch_Invoke (pthis, dispidMember, riid, lcid, wFlags, pdispparams, pvarResult, pexcepinfo, puArgErr) TO HRESULT
    FUNCTION = HRESULT
END FUNCTION
' ****************************************************************************************

[Cliff Nichols]

Thank You Steven,
This revamps my hopes of making things work.

and Thank You to Jose Roca!!!!

I will be trying this out today, and see how it goes. Along with figuring out how to late bind events from the Pb Dll.

[Steven Pringels 3]

Hi Cliff,

Jose Roca has a CallByName function... oh where is that again...

searching

ah here it is...

FUNCTION TB_CallByName ( _
    BYVAL pthis AS DWORD, _                                    ' *IDispatch
    BYVAL vNameOrId AS VARIANT, _                              ' Name or identifier
    BYVAL callType AS LONG, _                                  ' Call type
    BYREF vParams() AS VARIANT, _                              ' Array of variants
    BYREF vResult AS VARIANT, _                                ' Variant result
    BYREF pex AS EXCEPINFO _                                   ' EXCEPINFO structure
    ) EXPORT AS LONG                                           ' Error code

    DIM dw_puArgErr AS DWORD, DISPID_PROPERTYPUT AS LONG, IID_NULL AS GUID
    DIM vArgs(0) AS VARIANT, udt_DispParams AS DISPPARAMS
    DIM hr AS LONG, strName AS STRING, DispID AS LONG
    DIM nParams AS LONG, i AS LONG, idx AS LONG

    ' Check for null pointer
    IF pthis = 0 THEN FUNCTION = %E_POINTER : EXIT FUNCTION

    ' Get the DispID
    IF VARIANTVT(vNameOrId) = %VT_BSTR THEN
       strName = UCODE$(VARIANT$(vNameOrId))
       hr = IDispatch_GetIDOfName(pthis, strName, DispID)
       IF hr THEN
          FUNCTION = hr
          EXIT FUNCTION
       END IF
    ELSE
       DispID = VARIANT#(vNameOrId)
    END IF

    ' Copy the array in reversed order
    IF VARPTR(vParams()) THEN
       nParams = UBOUND(vParams) - LBOUND (vParams) + 1
       IF nParams > 0 THEN
          REDIM vArgs(nParams - 1)
          idx = nParams - 1
          FOR i = LBOUND(vParams) TO UBOUND(vParams)
             IF VARIANTVT(vParams(i)) = %VT_EMPTY THEN
                vArgs(idx) = ERROR %DISP_E_PARAMNOTFOUND
             ELSE
                vArgs(idx) = vParams(i)
             END IF
             DECR idx
             IF idx < 0 THEN EXIT FOR
          NEXT
       END IF
   END IF

   IF CallType = 4 OR CallType = 8 THEN  ' %DISPATCH_PROPERTYPUT and %DISPATCH_PROPERTYPUTREF
      DISPID_PROPERTYPUT = -3
      udt_DispParams.CountNamed = 1
      udt_DispParams.NamedDispId = VARPTR(DISPID_PROPERTYPUT)
   END IF

   udt_DispParams.CountArgs = nParams
   IF nParams > 0 THEN udt_DispParams.VariantArgs = VARPTR(vArgs(0))

   FUNCTION = IDispatch_Invoke(pthis, DispID, IID_NULL, 0, CallType, udt_DispParams, vResult, pex, dw_puArgErr)

END FUNCTION

[Cliff Nichols]

Steve,
I am using createobject, and have the dll registered and the typelibrary embeded.

I have learned I can call the method with "CallByName" in VB to solve the late binding, but "CallByName" appears to be a VB only function, so I need to find what the windows api behind the function is.

I am working on this, and how to expose events from the PB dll to the other language, but boyyyyyyyy is it taking a lot of trial and error to get this far

[Steve Rossell]

1. Are you using CreateObject in VB?
2. Did you embed the typelib as a resource in your dll using PBTYPE?
3. Did you regsvr32 the dll?

[Cliff Nichols]

I am having problems with a PB dll I am writing for use in other programming languages. I just can not seem to expose a method to the other languages except to do early binding in the other languages.

Is there a way to do late binding in other languages (VB to be more specific) so that I can call the objects method?