[Lazarus] TControl.Click?

[Hans-Peter Diettrich]

Mattias Gaertner schrieb:
> On Sat, 01 Oct 2011 08:39:42 +0100
> Martin <lazarus at mfriebe.de> wrote:
> 
>> On 01/10/2011 07:53, Mattias Gaertner wrote:
>>> On Sat, 01 Oct 2011 03:04:56 +0200
>>> Hans-Peter Diettrich<DrDiettrich1 at aol.com>  wrote:
>>>
>>>> I don't understand the logic behind TControl.Click:
>>>>
>>>> procedure TControl.Click;
>>>> begin
>>>>     //DebugLn(['TControl.Click ',DbgSName(Self)]);
>>>>     if (not (csDesigning in ComponentState)) and (ActionLink<>  nil) and
>>>>        ((Action=nil) or (@FOnClick<>  @Action.OnExecute) or
>>>> Assigned(FOnClick)) then
>>>>       ActionLink.Execute(Self)
>>>>     else
>>>>     if Assigned(FOnClick) then
>>>>       FOnClick(Self);
>>>> end;
>>>>
>>>>
>> Maybe I overlook something, but
>> @FOnClick is the address of the variable holding the method reference 
>> (or nil)
>> so is @Action.OnExecute
>>
>> So when can they ever be equal?
> 
> You are right.

Really?

AFAIK method pointers are handled differently in Delphi and FPC, where 
FPC requires @FOnClick to get the value stored in FOnClick, where Delphi 
guesses whether FOnClick should invoke the method or return the value.


>> Should that maybe compare FOnClick <> Action.OnExecute ?
> 
> That would miss difference in Data.
> I added a CompareMem.

IMO the comparison worked as-is, as found in several places in the LCL.

What about:

function TControlActionLink.IsOnExecuteLinked: Boolean;
begin
   Result := inherited IsOnExecuteLinked
             and (FClient.OnClick = Action.OnExecute);
end;


>> Also is that supposed to be a shortcut, saving the call, or is that 
>> indeed supposed to modify behaviour?
> 
> Good question. 
> I guess it would be enough to check (not (csDesigning in
> ComponentState)) and (ActionLink <> nil).
> 
> Maybe the Delphi docs have an answer.

No :-(

>> Even if the 2 callbacks are pointing to the same method, calling 
>> Action.OnExecute, will call the callback with Sender=TheAction, while 
>> FOnClick gets the current object.

Looks as if Execute should be overridden in TControlActionLink!

DoDi