Event callback behavior, buggy

[Unsigned 5]

This code correctly displays a message box containing "Hello!" on startup. If/when the tray item "Click Me" is clicked however, the script errors out with

(17) : ==> Variable used without being declared.

It would seem that parameters are ignored entirely when a function is used as a callback, even to the point of not setting the default parameter list.

While I can certainly think of technical reasons for this behavior (already given the lack of callback parameter support), the lack of warning can be unexpected and lead to a bit of a "gotcha" situation.

Actually, had it not been for AutoItSetOption("MustDeclareVars", 1), it would have taken much much longer to discover the problem. (This is a bare-bones example, the issue originally appeared in a fairly decent sized > 100KB script.)

I say buggy because this scenario (a callback function erroneously expecting parameters) is something that could (and should, IMHO) be caught at compile time by Au3Check (similar to the way it catches "undefined function" errors for missing callback functions).

AutoItSetOption("MustDeclareVars", 1)
Opt("TrayMenuMode", 11)
Opt("TrayOnEventMode", 1)
TraySetClick(16)
 
TrayCreateItem("Click Me")
TrayItemSetOnEvent(-1, "ShowMessage")
TrayCreateItem("Exit")
TrayItemSetOnEvent(-1, "DoExit")
TraySetState()
 
Func DoExit()
    Exit
EndFunc
 
Func ShowMessage($message = "Default message here")
    MsgBox(0, "ShowMessage()", $message)
EndFunc
 
ShowMessage("Hello!")
 
While 1
    Sleep(250)
WEnd
Exit

[BrewManNH 1,149]

I just found this out last week after a year of using the language, OnEvent functions can NOT have any parameters, even default parameters. You'd have to have the OnEvent event pointing to a function with no parameters, and have that one call your function that does have them.

AutoItSetOption("MustDeclareVars", 1)
Opt("TrayMenuMode", 11)
Opt("TrayOnEventMode", 1)
TraySetClick(16)
TrayCreateItem("Click Me")
TrayItemSetOnEvent(-1, "ShowMessage1")
TrayCreateItem("Exit")
TrayItemSetOnEvent(-1, "DoExit")
TraySetState()
Func DoExit()
 Exit
EndFunc
Func ShowMessage1(); <<<<<<<<<<<< new function, no parameter
 ShowMessage() ; Call your function with a parameter from here
EndFunc
Func ShowMessage($message = "Default message here")
 MsgBox(0, "ShowMessage()", $message)
EndFunc
ShowMessage("Hello!")
While 1
 Sleep(250)
WEnd
Exit

[Unsigned 5]

Yep, I already ended up going that route.

[martin 72]

For some situations my OnEvent udf can help because it allows parameters. It gives a single function which can be used in place of GuiCtrlSetOnEvent, GuiSetOnEvent and HotkeySet. The functions for the events can have a variable number of parameters.