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Event callback behavior, buggy

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Unsigned

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

.

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BrewManNH

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

If I posted any code, assume that code was written using the latest release version unless stated otherwise. Also, if it doesn't work on XP I can't help with that because I don't have access to XP, and I'm not going to.
Give a programmer the correct code and he can do his work for a day. Teach a programmer to debug and he can do his work for a lifetime - by Chirag Gude
How to ask questions the smart way!

I hereby grant any person the right to use any code I post, that I am the original author of, on the autoitscript.com forums, unless I've specifically stated otherwise in the code or the thread post. If you do use my code all I ask, as a courtesy, is to make note of where you got it from.

Back up and restore Windows user files _Array.au3 - Modified array functions that include support for 2D arrays.  -  ColorChooser - An add-on for SciTE that pops up a color dialog so you can select and paste a color code into a script.  -  Customizable Splashscreen GUI w/Progress Bar - Create a custom "splash screen" GUI with a progress bar and custom label.  -  _FileGetProperty - Retrieve the properties of a file  -  SciTE Toolbar - A toolbar demo for use with the SciTE editor  -  GUIRegisterMsg demo - Demo script to show how to use the Windows messages to interact with controls and your GUI.  -   Latin Square password generator

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Unsigned

Yep, I already ended up going that route. :graduated:


.

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martin

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.


Serial port communications UDF Includes functions for binary transmission and reception.printing UDF Useful for graphs, forms, labels, reports etc.Add User Call Tips to SciTE for functions in UDFs not included with AutoIt and for your own scripts.Functions with parameters in OnEvent mode and for Hot Keys One function replaces GuiSetOnEvent, GuiCtrlSetOnEvent and HotKeySet.UDF IsConnected2 for notification of status of connected state of many urls or IPs, without slowing the script.

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