Trap second instance of running script

[CarlD]

In my thread entitled Newbie template for assigning script to hotkey, I was rightly chastised for failing to include error-checking that would trap an attempt to launch a second instance of the script, which then would not be responsive to the hotkey for terminating the script. Forum member Exit set me straight with his _Hotkey function, which does just that (and which I've incorporated into my "template"):

; Code by forum member Exit
_HotKey("{ESC}")
_HotKey("^b")
Func _HotKey($hotkey = "")
;       ! ALT  + SHIFT  ^ CONTROL  # WinKey

    Switch @HotKeyPressed

        Case "{ESC}"
            Exit 0*MsgBox(64 + 262144, Default, "Exit", 1)
        Case "^b"
            Beep()
            ; delete ";" to temporarely disable hotkey

            ; HotKeySet(@HotKeyPressed)
            ; send("^b")
            ; HotKeySet(@HotKeyPressed,"_Hotkey")
        Case Else
            If Not IsDeclared("hotkey") Then Return MsgBox(16 + 262144, Default, "No CASE statement defined for hotkey " & @HotKeyPressed)
            If HotKeySet($hotkey, "_Hotkey") = 0 Then Return MsgBox(16 + 262144, Default, "Hotkey " & $hotkey & " invalid or set by another application.")
    EndSwitch

EndFunc   ;==>_HotKey



While Sleep(100)     ; here should be your application.
WEnd                 ; meanwhile, here is a dummy loop.

It occurred to me that an alternate way of doing this, involving less code, might be:

#include <Misc.au3>

If _Singleton(@ScriptName, 1) = 0 Then
    MsgBox(64, @ScriptName, @ScriptName & " is already running!", 2)
    Exit
EndIf

Are there advantages/disadvantages to this alternate method?

Thanks in advance for your help.

PS: Private message sent to Exit alerting him to this thread.

Edited June 10, 2015 by CarlD

[CarlD]

[Duplicate post removed]

Edited June 10, 2015 by CarlD

[argumentum]

Exit was right, his code will show a FAIL even if the key is taken by another script or any cause of failure.

[CarlD]

Exit was right, his code will show a FAIL even if the key is taken by another script or any cause of failure.

​Got it. Thanks!

[Exit]

It occurred to me that an alternate way of doing this, involving less code, might be:

#include <Misc.au3>
If _Singleton(@ScriptName, 1) = 0 Then MsgBox(64, @ScriptName, @ScriptName & " is already running!", 2)
     Exit
EndIf

Are there advantages/disadvantages to this alternate method?

This way does not help​ when the hotkey is set by another application or by system.
Just try to set F12. It is reserved to system. See also help file.

_HotKey("{ESC}")
_HotKey("{F12}")
Func _HotKey($hotkey = "")
    Switch @HotKeyPressed

        Case "{ESC}"
            Exit 0 * MsgBox(64 + 262144, Default, "Exit", 1)
        Case "{F12}"
            Beep()
        Case Else
            If Not IsDeclared("hotkey") Then Return MsgBox(16 + 262144, Default, "No CASE statement defined for hotkey " & @HotKeyPressed)
            If HotKeySet($hotkey, "_Hotkey") = 0 Then Return MsgBox(16 + 262144, Default, "Hotkey " & $hotkey & " invalid or set by another application.")
    EndSwitch

EndFunc   ;==>_HotKey



While Sleep(100) ; here should be your application.
WEnd ; meanwhile, here is a dummy loop.

 

[CarlD]

Exit, thanks. I also noticed that your function actually prevents a second instance of the script from opening, whereas the _Singleton statement takes effect in the second instance (but quickly shuts it down). Your _Hotkey function is very instructive -- thanks again.