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List:       ms-atl
Subject:    Re: Passing GUIDs as Method Arguments
From:       Stan Gibbs <stan_gibbs () OM ! CV ! HP ! COM>
Date:       1997-07-31 19:00:53
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     IErrorInfo is not an oleautomation compatible interface (it doesn't
     have the [oleautomation] attribute in oaidl.idl), so GUID is allowed.

     Stan


______________________________ Reply Separator _________________________________
Subject: Re: Passing GUIDs as Method Arguments
Author:  Non-HP-ATL (ATL@LISTSERV.MSN.COM) at HP-Corvallis,mimegw1
Date:    7/31/97 9:14 AM


How is this defined in the IDL? Whenever, I define a method to pass a
GUID, I get the following MIDL compiler error.

interface IPassGuid : IDispatch
{
        [id(1), helpstring("method PassGuid")] HRESULT PassGuid([out]
GUID* lpGuid);
};

.\guid.idl(24) : warning MIDL2039 : interface does not conform to
[oleautomation] attribute : [ Parameter 'lpGuid' of Procedure 'PassGuid'
( Interface 'IPassGuid' ) ]

However, this is exactly the way the following interface is defined in
Oaidl.idl:

interface IErrorInfo: IUnknown
{
    typedef [unique] IErrorInfo * LPERRORINFO;

    HRESULT GetGUID(
                [out] GUID * pGUID
            );


> -----Original Message-----
> From: Anne Chinn (RhoTech) [SMTP:a-annech@MICROSOFT.COM]
> Sent: Thursday, July 31, 1997 11:32 AM
> To:   ATL@LISTSERV.MSN.COM
> Subject:      Re: Passing GUIDs as Method Arguments
>
> The Repository interfaces pass around GUIDs as VARIANTS.  The
> data is stored as a SAFEARRAY of VT_UI1.  When packaging up a GUID
> to send you use the class below, CGuidVariant, which will initialize
> the
> SAFEARRAY with the GUID.  When unpackaging you would just extract
> the GUID from the VARIANT using the SafeArrayAccessData methods.
>
>
> Packaging GUID into a VARIANT:
>
>         CGuidVariant v(CLSID_SOMEOBJECT);
>
> Unpackaging GUID from VARIANT:
>
>         CComVariant guid_variant;
>         GUID *guid;
>
>         if (FAILED(hr = SafeArrayAccessData(guid_variant.parray,
> (void**)&guid)))
>                 ReturnError(hr);
>
>         if (FAILED(hr = SafeArrayUnaccessData(guid_variant.parray)))
>                 ReturnError(hr);
>
>
> CGuidVariant class initializes the parray member of the VARIANT with
> the
> GUID.
>
> class CGuidVariant : public CComVariant
> {
> public:
>         CRepVariant() :
>                 CComVariant()
>         {
>         }
>
>         CRepVariant(REFGUID guid)
>         {
>                 ::VariantInit(this);
>                 InitSafeArrayLen((BYTE *)&guid, sizeof(GUID));
>         }
>
>         CRepVariant &operator=(REFGUID guid)
>         {
>                 ::VariantClear(this);
>                 InitSafeArrayLen((BYTE *)&guid, sizeof(GUID));
>                 return (*this);
>         }
>
>         inline SAFEARRAY * InitSafeArrayLen(BYTE *pData, size_t iSize)
>         {
>                 if ((this->parray = AllocSafeArrayLen(pData, iSize))
> !=
> NULL)
>                         this->vt = VT_UI1 | VT_ARRAY;
>                 else
>                 {
>                         this->vt = VT_EMPTY;
>                 }
>                 return (this->parray);
>         }
> };
>
> inline SAFEARRAY *AllocSafeArrayLen(    // Return status.
>         BYTE            *pData,                                 //
> Data
> to be placed in the array.
>         size_t          iSize)                                  //
> Size
> of data.
> {
>         SAFEARRAYBOUND sBound;                          // Used to
> fill
> out the bounds.
>         SAFEARRAY       *pArray = 0;                    // Ptr to the
> new array.
>
>         sBound.cElements = iSize;
>         sBound.lLbound = 0;
>         if ((pArray = SafeArrayCreate(VT_UI1, 1, &sBound)) != NULL)
>                 memcpy(pArray->pvData, (void *) pData, iSize);
>         return (pArray);
> }
>
> Anne
>
> > -----Original Message-----
> > From: Shailesh Shah [SMTP:Shailesh_Shah@INFINIUM.COM]
> > Sent: Thursday, July 31, 1997 7:51 AM
> > To:   ATL@LISTSERV.MSN.COM
> > Subject:      Re: Passing GUIDs as Method Arguments
> >
> > >>Does anyone have any code snippets that pass guids as arguments in
> > an
> > >>interface method back and forth from an ATL local server(EXE) to a
> > VB5.0
> > >>client?
> >
> > AFAIK, VB doesnt support non-automation typs such as GUID.
> >
> > ----------------------------------------------------------------
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