MessageDlg inside Try..Finally

[dpfmp]

Hi,

// test

procedure TMainForm.UniButton1Click(Sender: TObject);
var
  iArr: array of integer;
begin
   SetLength(iArr,2);
   try

     MessageDlg('Yes or No', mtConfirmation, mbYesNo,
     procedure (Sender: TComponent; Res: integer)
      begin
        case Res  of
          TModalResult(mrYes):  iArr[0] := 0;   // <-- AV
          TModalResult(mrNo):   iArr[1] := 1;  // <-- AV
        end
      end);

   finally
     SetLength(iArr,0);
   end;
end;

 

The code reaches the "Finally" block before MessageDlg shows up and causes an AV since the array was freed.  What if we need to change a dynamically created structure ( memory table, array etc ) inside a "try..finally" by calling a function in the MessageDlg callback that would modify the structure?  

Is this the wrong approach?

Thank you,

Denis Prince 

D10.1 UniGUI 1.50.0.1484

[Sherzod]

Hi,

Please see the documentation:

http://unigui.com/doc/online_help/synch-and-asynch-operations.htm

[dpfmp]

Hi Sherzod,

 

EnableSynchronousOperations true

 

Not blocking the thread

=================================================

procedure TMainForm.UniButton1Click(Sender: TObject);
var
  iArr: array of integer;
begin
   SetLength(iArr,2);
   try
     MessageDlg('Yes or No', mtConfirmation, mbYesNo,
       procedure (Sender: TComponent; Res: integer)
       begin
         case Res  of
           TModalResult(mrYes):  iArr[0] := 0;    // <-- AV
           TModalResult(mrNo):   iArr[1] := 1;    // <-- AV
        end
      end);

   finally
     SetLength(iArr,0);
   end;
end;

 

Blocking the thread  (this works fine in my test)

================================================

procedure TMainForm.UniButton2Click(Sender: TObject);
var
  iArr: array of integer;
  Res: TModalResult;
begin
  SetLength(iArr,2);
  try

    Res := MessageDlg('Yes or No', mtConfirmation, mbYesNo);
    case Res of
      mrYes:  iArr[0] := 0;
      mrNo:   iArr[1] := 1;
    end

  finally
    SetLength(iArr,0);
  end;
end;

Do we use the callback in MessageDlg when we don't want to block the thread?

 

Thank you again for your help,

Denis Prince