Global variable not being updated

ahha · February 25, 2023

I've whittled down a program to illustrate where my problem is.
I've been staring at the code and simply am missing something that when I see it pointed out to me will be a DUH moment.

On line 14 I declare $file a Global and init it to null "".
Line 37 has a Case $idFileMenu_Open where I invoke $file = FileOpenDialog at line 52.
When I return to the Case statement $file is null ("") instead of a filename.

Running the program (and selecting any .txt file) will message out the $file value at each point.

Any comments welcome as I'm stumped

;author: ahha - not so bright :(
;file: Open File issue v1e.au3
#AutoIt3Wrapper_run_debug_mode=Y    ;use this to debug in console window <--- LOOK, ;RECALL ;debug will toggle it on/off so use: ; debug if needed

Opt("MustDeclareVars", 1) ;0=no, 1=require pre-declaration

#include <File.au3>
#include <GUIConstantsEx.au3>
#include <GUIEdit.au3>
#include <WindowsConstants.au3>

Global $data = ""
Global $file = ""   ;is the full path filename like 'C:\Program Files (x86)\AutoIt3\...\123.txt'
Global $cIDFormTextEditorTitle = "* Untitled"   ;init value

;==== set up the GUI and the Edit control ====
Global $hFormTextEditor = GUICreate($cIDFormTextEditorTitle, 920, 570, -1, -1, BitOR($WS_MAXIMIZEBOX, $WS_MINIMIZEBOX, $WS_SIZEBOX), $WS_EX_CLIENTEDGE)     ;handle
Global $cIDTextEdit = GUICtrlCreateEdit("", -2, -2, 921, 528, BitOR($ES_AUTOVSCROLL, $ES_WANTRETURN, $WS_VSCROLL, $ES_NOHIDESEL))   ;control ID ;-2 line up left, -2 line up top, +1 width, +1 bottom
GUISetState(@SW_SHOW, $hFormTextEditor)     ;display the GUI

;File Menu
Local $idFileMenu = GUICtrlCreateMenu("&File")  ;Create the file menu. This is the main menu and will have the sub-menus.  Underline F when ALT is pressed. ;Main menu
    ;sub-menus
    Local $idFileMenu_Open      = GUICtrlCreateMenuItem("&Open", $idFileMenu)   ;Create the "Open" menu item.

_GUICtrlEdit_SetText($cIDTextEdit, $data)   ;display any file contents read in from like a command line filename

Local $nMsg

;MAIN loop
While 1
    $nMsg = GUIGetMsg()     ;Check what's happening in the GUI (Graphical User Interface)
    If $nMsg <> 0 Then  ;we have a message so
        Switch $nMsg    ;Check for GUI events
            ;Check File menu ---
            Case $idFileMenu_Open       ;Open menu item clicked, or shortcut keys Ctrl+O = Open pressed
                Pause("Start: Case $idFileMenu_Open $file = '" & $file & "'")
                _Open("")       ;let user pick it if $file = ""
                Pause("End: Case $idFileMenu_Open $file = '" & $file & "'")
            Case $GUI_EVENT_CLOSE
                Exit
        EndSwitch   ;End running through GUI events.
    EndIf
WEnd    ;End main body loop


;File menu functions ========
Func _Open($file)       ;_Open("")  ;let user pick it v2cd
    Pause("In: Func _Open($file), $file = '" & $file & "'")
    If $file = "" Then  ;let user pick the file
        $file = FileOpenDialog("Open",@WorkingDir,"text (*.txt)| all (*.*)")    ;Start an open file dialog. Define text files (*.txt) as one filter, define all files (*.*) as a second filter.
        Pause("$file = '" & $file & "'")
    EndIf

    $data = FileRead($file)     ;Read the data of the file
    _GUICtrlEdit_SetText($cIDTextEdit, $data)   ;Set the data to be displayed
    $cIDFormTextEditorTitle = _GetShortFileName($file)      ;set title with short filename
    WinSetTitle($hFormTextEditor, "", $cIDFormTextEditorTitle)
    Pause($file &@CRLF& "Read into editor.")
EndFunc     ;Func _Open()

;misc functions ========
Func _GetShortFileName($sfullfilename)
    Local $sDrive, $sDir, $sFileName, $sExtension   ;for use by _PathSplit
    Local $aPathSplit = _PathSplit($sfullfilename, $sDrive, $sDir, $sFileName, $sExtension)
    Return($aPathSplit[3] & $aPathSplit[4]) ;return the short filename
EndFunc     ;Func _GetShortFileName($sfullfilename)

Func  Pause($text="")
    ;__scrolltext("Debug: Paused " & $text & @CRLF)
    MsgBox(262144, "DEBUG", "Paused: " & $text)
EndFunc     ;Func  Pause($text="")

Danp2 · February 25, 2023

28 minutes ago, ahha said:

Func _Open($file)

This creates a local variable named $file, so your global variable is never updated. You will either need to rename this variable or restructure your function so that it returns a value that can then be assigned to the global $file.

ahha · February 25, 2023

@Danp2I don't understand how Func _Open creates a local. I've assigned a Global $file to receive the user picked filename. Can you explain further which functions create a local?

ahha · February 25, 2023

@Danp2Now I understand. By using _Open($file) $file became a local. By changing it to _Open($xfile) then everything works. For reference code below. Thanks - it was a DUH moment.

;author: ahha - not so bright :(
;file: Open File issue v1e.au3
#AutoIt3Wrapper_run_debug_mode=Y    ;use this to debug in console window <--- LOOK, ;RECALL ;debug will toggle it on/off so use: ; debug if needed

Opt("MustDeclareVars", 1) ;0=no, 1=require pre-declaration

#include <File.au3>
#include <GUIConstantsEx.au3>
#include <GUIEdit.au3>
#include <WindowsConstants.au3>

Global $data = ""
Global $file = ""   ;is the full path filename like 'C:\Program Files (x86)\AutoIt3\...\123.txt'
Global $cIDFormTextEditorTitle = "* Untitled"   ;init value

;==== set up the GUI and the Edit control ====
Global $hFormTextEditor = GUICreate($cIDFormTextEditorTitle, 920, 570, -1, -1, BitOR($WS_MAXIMIZEBOX, $WS_MINIMIZEBOX, $WS_SIZEBOX), $WS_EX_CLIENTEDGE)     ;handle
Global $cIDTextEdit = GUICtrlCreateEdit("", -2, -2, 921, 528, BitOR($ES_AUTOVSCROLL, $ES_WANTRETURN, $WS_VSCROLL, $ES_NOHIDESEL))   ;control ID ;-2 line up left, -2 line up top, +1 width, +1 bottom
GUISetState(@SW_SHOW, $hFormTextEditor)     ;display the GUI

;File Menu
Local $idFileMenu = GUICtrlCreateMenu("&File")  ;Create the file menu. This is the main menu and will have the sub-menus.  Underline F when ALT is pressed. ;Main menu
    ;sub-menus
    Local $idFileMenu_Open      = GUICtrlCreateMenuItem("&Open", $idFileMenu)   ;Create the "Open" menu item.

_GUICtrlEdit_SetText($cIDTextEdit, $data)   ;display any file contents read in from like a command line filename

Local $nMsg

;MAIN loop
While 1
    $nMsg = GUIGetMsg()     ;Check what's happening in the GUI (Graphical User Interface)
    If $nMsg <> 0 Then  ;we have a message so
        Switch $nMsg    ;Check for GUI events
            ;Check File menu ---
            Case $idFileMenu_Open       ;Open menu item clicked, or shortcut keys Ctrl+O = Open pressed
                Pause("Start: Case $idFileMenu_Open $file = '" & $file & "'")
                _Open("")       ;let user pick it if $file = ""
                Pause("End: Case $idFileMenu_Open $file = '" & $file & "'")
            Case $GUI_EVENT_CLOSE
                Exit
        EndSwitch   ;End running through GUI events.
    EndIf
WEnd    ;End main body loop


;File menu functions ========
Func _Open($xfile)      ;_Open("")  ;let user pick it v2cd
    Pause("In: Func _Open($file), $file = '" & $file & "'")
    If $xfile = "" Then ;let user pick the file
        $file = FileOpenDialog("Open",@WorkingDir,"text (*.txt)| all (*.*)")    ;Start an open file dialog. Define text files (*.txt) as one filter, define all files (*.*) as a second filter.
        Pause("$file = '" & $file & "'")
    EndIf

    $data = FileRead($file)     ;Read the data of the file
    _GUICtrlEdit_SetText($cIDTextEdit, $data)   ;Set the data to be displayed
    $cIDFormTextEditorTitle = _GetShortFileName($file)      ;set title with short filename
    WinSetTitle($hFormTextEditor, "", $cIDFormTextEditorTitle)
    Pause($file &@CRLF& "Read into editor.")
EndFunc     ;Func _Open()

;misc functions ========
Func _GetShortFileName($sfullfilename)
    Local $sDrive, $sDir, $sFileName, $sExtension   ;for use by _PathSplit
    Local $aPathSplit = _PathSplit($sfullfilename, $sDrive, $sDir, $sFileName, $sExtension)
    Return($aPathSplit[3] & $aPathSplit[4]) ;return the short filename
EndFunc     ;Func _GetShortFileName($sfullfilename)

Func  Pause($text="")
    ;__scrolltext("Debug: Paused " & $text & @CRLF)
    MsgBox(262144, "DEBUG", "Paused: " & $text)
EndFunc     ;Func  Pause($text="")

mistersquirrle · February 25, 2023

Yes, if you name a variable as a function parameter or Local the same name as a Global variable, the function will use your Local version instead, and will not access/update/change/whatever to the Global variable. The Global variable basically will not exist while that function runs.

I recommend that you check out this page: https://www.autoitscript.com/wiki/Best_coding_practices

It has some naming tips for variables, such as $g_iSomeVar for a Global variable, and $iSomeVar for the local version. Your change of $xfile works, but what is x? Does it have any meaning? If it works for you, great, otherwise going along with a standard is a good idea, if you can (IMO).

Edited February 25, 2023 by mistersquirrle

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Global variable not being updated

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