[DUG] Returning a WideString in an Invoke Param

[Conor Boyd]

I just use WideStrings in COM parameters without any conversions at all
in D7 and BDS2006.

However, is TDispParams a class?

Surely you'll have to do some sort of streaming for the TDispParams
type?

C.

-----Original Message-----
From: delphi-bounces at ns3.123.co.nz [mailto:delphi-bounces at ns3.123.co.nz]
On Behalf Of Phil Middlemiss

I have an automation object with events. One of the events has a couple
of VAR parameters which I'm not quite sure how to handle. Here is the
code that is NOT working:

procedure TT3SDKEvents.DoInvoke(Sender : TObject; DispID: Integer; const
IID: TGUID;
  LocaleID: Integer; Flags: Word; var Params: TDispParams; VarResult,
ExcepInfo,
  ArgErr: Pointer);
    case DispID of

    ...

    4: { OnIdentify }
      if assigned(FOnIdentify) then
        begin
        //initialise the values
        layermanagerid :=  WideCharToString(Params.rgvarg[1].bStrVal);
        appname := WideCharToString(Params.rgvarg[0].bstrVal);
        if assigned(FOnIdentify) then
          FOnIdentify(layermanagerid, appname);
        Params.rgvarg[1].bstrVal := PWideChar(layermanagerid);
        Params.rgvarg[0].bstrVal := PWideChar(appname);
        end;
    end;
end;

The above code just ends up returning an empty string - I've checked to
make sure that the call to FOnIdentify is indeed returning values.
So the question is: how should I be returning a widestring in the
TDispParams?