Crash on GUICtrlSetOnEvent and optional function parameter

[okolaris]

Hey everyone,

when using GUICtrlSetOnEvent and a function that has (for example) a single optional parameter the program exits with "Variable used without being declared". While this can be avoided by using the "IsDeclared"-Statement in named function, I was wondering why this behavior is favored. In the helpfile I could only find the statement: "You can not call a function using parameters.", which is not my intent.

Here a small example:

#include <GUIConstants.au3>

Opt("GUIOnEventMode", 1)
GUICreate('Test', 465, 269, -1, -1)
GUISetOnEvent($GUI_EVENT_CLOSE, "End")
GUICtrlCreateButton('test', 192, 159, 80, 80)
GUICtrlSetOnEvent(-1, "Test")
GUISetState(@SW_SHOW)

While 1
    Sleep(100)
WEnd


Func Test($bMsg = True)
;~  If Not IsDeclared("bMsg") Then $bMsg = True
    If $bMsg Then MsgBox(0, '', 'test')
EndFunc

Func End()
    Exit
EndFunc

Thanks!

[BrewManNH]

From the help file:

Quote

You can not call a function using parameters.

 

[okolaris]

Personally I understand that as "you can not pass parameters to a function using GUICtrlSetOnEvent". If that does not mean what I expected, I am sorry for this unnecessary post. I would however still recommend adjusting this article to clearify that for not native english speakers.

[BrewManNH]

4 minutes ago, okolaris said:

Personally I understand that as "you can not pass parameters to a function using GUICtrlSetOnEvent".

It means both.

You can't use a function with parameters, and you can't pass any parameters to it. The parameters in the function definition are ignored when you use SetOnEvent or AdlibRegister. And if you try to make use of the variable inside the called function, you get an error because it was ignored in the function declaration.

Well, technically, you CAN use a function with parameters, just don't try to use them if you do that. Which makes using them pointless.

[okolaris]

Thanks for clearification!

Is there a specific reason (besides the official statement in the help file) why even a funtion's definitions with only optional parameters is ignored? Or is it just because it has been declared like that? Obviously I personally expected a different result at first.

[farouk12]

I didn't expect that 

[okolaris]

Just now, farouk12 said:

I didn't expect that 

Well I guess you understood the help file in the first place xD

I would have expected it to be the same as calling Test().

[lee321987]

Just sharing my workaround.  Let me know if anyone thinks this is a bad idea:

Func _my_func($bVar = True)
    Eval("bVar")
    If @error Then
        $bVar = True
    EndIf
    ConsoleWrite($bVar & @CRLF)
EndFunc

 

[VAN0]

So, then what's the point of having "optional" parameters? I mean, if the function called without parameters, the optional parameter variable should be defined with the provided default value, how is calling the function from an event that doesn't pass any parameters any different than just calling a function?