Pascal Script, how to return var parameter from script into my Delphi code?

Question

I need to modify function parameter variable (string) in my Pascal Script code and get it in the Delphi function, after the script finish it's work.

My script code:

function OnBroadcastMessage(iCID, iUIN: integer; var sUsersList: string; dtActualTo: double; bMustRead, bReadNotify: boolean; sMsg: string): boolean;
begin
  sUsersList := '3';
  result := true;
end;

begin

end.

My Delphi XE3 code (only tiny example, without any checks):

var
  Compiler: TPSPascalCompiler;
  Exec: TPSExec;
  ProcNo: cardinal;
  ParamList: TIfList;
  Data: AnsiString;
begin
  Compiler := TPSPascalCompiler.Create;
  Compiler.Compile(Script)
  Compiler.GetOutput(Data); 
  Compiler.Free;

  Exec.LoadData(Data);

  ProcNo := Exec.GetProc('OnBroadcastMessage');
  ParamList := TIfList.Create;

  ParamList.Add(@iCID);
  ParamList.Add(@iUIN);
  ParamList.Add(@sUsersList);
  ParamList.Add(@dtActualTo);
  ParamList.Add(@bMustRead);
  ParamList.Add(@bReadNotify);
  ParamList.Add(@sMsg);

  result := Exec.RunProc(ParamList, ProcNo);

  FreePIFVariantList(ParamList);
end;

This solution was wrong, I'm got an error at line "result := Exec.RunProc(ParamList, ProcNo);".

"Project mcserv.exe raised exception class $C0000005 with message 'access violation at 0x00a56823: read of address 0x0000000d'.".

How I do wrong?

*got an error* is totally useless unless you tell us what error you get. What is the **exact** error message you're getting?? — Ken White, Nov 04 '16 at 19:13
Sorry. Ken. Error text: "Project mcserv.exe raised exception class $C0000005 with message 'access violation at 0x00a56823: read of address 0x0000000d'.". — HobitZlobny, Nov 05 '16 at 11:25
I've never used a Pascal Script, but I can see that Exec has not been initialized. Try Exec := tPSExec.Create; — David Dubois, Nov 05 '16 at 11:48
David, all ok, Exec was created early, not in this function, — HobitZlobny, Nov 05 '16 at 12:40
But we should not be confronted by that doubt. A MCVE would avoid that. — David Heffernan, Nov 06 '16 at 08:07

Christophe Fardeau · Accepted Answer · 2016-11-05T12:28:54.800

You need to create PPSVariant for string parameters :

Param := CreateHeapVariant(fExec.FindType2(btString));
PPSVariantAString(Param).Data := AnsiString('test value');

Another way is to work with Exec.RunProcPVar() method. You just have to define an array of variant with your parameters :

var
  vparams : array of Variant;
begin
  Compiler := TPSPascalCompiler.Create;
  Compiler.Compile(Script);
  Compiler.GetOutput(Data);
  Compiler.Free;

  Exec.LoadData(Data);

  ProcNo := Exec.GetProc('OnBroadcastMessage');

  SetLength(vparams, 7);
  vparams[0] := iCID;
  vparams[1] := iUIN;
  vparams[2] := sUsersList;
  vparams[3] := dtActualTo;
  vparams[4] := bMustRead;
  vparams[5] := bReadNotify;
  vparams[6] := sMsg;

  Result := Exec.RunProcPVar(vparams, procno);

end;

Pascal Script, how to return var parameter from script into my Delphi code?

1 Answers1