[solved] bug? with (panel)mouseup

[speter]

I've noticed a minor issue with the mouseup event, in panels and maybe other components.

I've attached a project which has 2 panels; both with onmouseup event methods. Each calls a procedure which lists the x,y coord in a memo. The only difference is that I have commented out some of the parameters - to remove the "Parameter "Button" not used" Hint.

When the user clicks in the first panel the displayed coord is 0,0.

Code: Pascal  [Select][+][-]

1. procedure TForm1.showxy(sender:TObject; x,y : integer);
2. var
3.   panel : TPanel;
4. begin
5.   panel := TPanel(sender);
6.   memo1.append(format('%s %d,%d',[panel.name,x,y]));
7. end;
8.  
9. procedure TForm1.Panel_leftMouseUp(Sender: TObject; {Button: TMouseButton;
10.   Shift: TShiftState;} X, Y: Integer);
11. begin
12.   showxy(sender,x,y);
13. end;
14.  
15. procedure TForm1.Panel_rightMouseUp(Sender: TObject; Button: TMouseButton;
16.   Shift: TShiftState; X, Y: Integer);
17. begin
18.   showxy(sender,x,y);
19. end;

This behaviour is with Lazarus v4.0 / Windows 11.

cheers
S.

[Martin_fr]

You can't modify the procedure declaration.

The caller will always sent all parameters.

If you remove some, then the parameters are still in the memory (or CPU registers). So if you remove "Button", then the value that is sent for "Button" ends up in "X, y". And that obviously wont be the expected value.


Procedure/Functions used in events (set by the form designer / object inspector) are not checked for having the correct param list. They are created once for you. If you change them, then things fail. (and may even crash).

[Bart]

The IDE should safeguard users from doing that.
IIRC then Delphi does so.

Bart

[speter]

You can't modify the procedure declaration.

The caller will always sent all parameters.

Thanks. I thought that since it compiled, it was allowed for.

The IDE should safeguard users from doing that.
IIRC then Delphi does so.

Agree, but I guess that is a feature request.

cheers
S.

[Bart]

Agree, but I guess that is a feature request.

There's a bugreport about it already.

Bart

[lazer]

You can't modify the procedure declaration.

The caller will always sent all parameters.

If you remove some, then the parameters are still in the memory (or CPU registers). So if you remove "Button", then the value that is sent for "Button" ends up in "X, y". And that obviously wont be the expected value.


Procedure/Functions used in events (set by the form designer / object inspector) are not checked for having the correct param list. They are created once for you. If you change them, then things fail. (and may even crash).

That is insanely silly in what is supposed to be a strictly typed language.  Though I suppose the strings fiasco broke that principal long ago. 

However, this topic has explained to me how you can get away with supplying two arguments to a method defined with three. That always looked like C style functions which is not possible in Pascal.

[Thaddy]

Turn the hint simply off:project options|compiler|messages
Or in code:

Code: [Select]

{$warn 5024 off}or on the commandline

Code: Bash  [Select][+][-]

1. fpc -vm5024 yourprogram.pas

[lazer]

Turn the hint simply off:project options|compiler|messages

I know a guy who had a problem with the oil pressure warning light flickering on and off all the time.
He concluded it was a wiring fault and removed the bulb.

Can you guess what happened next?

[jamie]

Turn the hint simply off:project options|compiler|messages

I know a guy who had a problem with the oil pressure warning light flickering on and off all the time.
He concluded it was a wiring fault and removed the bulb.

Can you guess what happened next?

If it was a Ford, there is no guessing required.!

[lazer]

No. Folksvagen, try again. 

Nice air cooled engine. Heading north from Alice Springs in November.

[jamie]

Oh, aren't those the ones you need a pull cord on to start them?

Jamie

[speter]

No. Folksvagen, try again. 

Nice air cooled engine. Heading north from Alice Springs in November.

Wow, that's a lovely drive, so long as you do it during the middle of the night - spend the days at 3-ways and Katherine; avoiding dawn / dusk at all costs (roo's made a real mess of anything without serious bull-bars).