Global variable does not have global scope

Question

supposedlyGlobalVariable := "blah"

ARoutine()
{
   localVariable := "asdf"
   MsgBox, The global variable value is %supposedlyGlobalVariable%.  The local variable value is %localVariable%.
}


^!X:: ;This assigns the hotkey CTRL + ALT + X to run the routine
ARoutine()
return

Run the code and the result is:

"The global variable value is .  The local variable value is asdf."

The documentation states:

Variable scope and declarations: With the exception of local variables in functions, all variables are global; that is, their contents may be read or altered by any part of the script.

Why does my global variable not have scope within the function?

Answer 1

The documentation for global variables can be found here:
https://autohotkey.com/docs/Functions.htm#Global

Global variables

To refer to an existing global variable inside a function (or create a new one), declare the variable as global prior to using it. For example:

LogToFile(TextToLog)
{
    global LogFileName
    FileAppend, %TextToLog%`n, %LogFileName%
}

I believe the concept of global, with AHK, is a bit different than in other languages. With AHK you can create a variable and use it within multiple hotkeys, and subroutines, without declaring it as global.

Gv := 0

f1::SetTimer, Action, % (on:=!on) ? (1000) : ("Off")

Action:
    Gv++
    trayTip,, % Gv
Return

f2::Msgbox, % Gv

Explaination of code:

• The F1 key toggles a timer to run the subroutine: Action every 1000ms.
• % starts an expression.
• on:=!on reverses the binary value of variable on every time F1 is pressed.
• ?: together is called the ternary operator.
• When on=1 delay is set to 1000ms; when on=0 the timer is turned Off.

The ++ operator adds 1 to variable Gv.

Answer 2

This makes things easier:

https://www.autohotkey.com/docs/Functions.htm#SuperGlobal

Super-global variables [v1.1.05+]: If a global declaration appears outside of any function, it takes effect for all functions by default (excluding force-local functions). This avoids the need to redeclare the variable in each function. However, if a function parameter or local variable with the same name is declared, it takes precedence over the global variable. Variables created by the class keyword are also super-global.

Just declare your variable as global in the main script:

global supposedlyGlobalVariable := "blah"

Answer 3

P.Brian, It works when you do this.. I know it doesn't explain why, but this might be your workaround.

#Persistent
GlobalVariable = "blah"
RETURN

ARoutine:
{
   localVariable := "asdf"
   MsgBox, The global variable value is %GlobalVariable%.  The local variable value is %localVariable%.
}
Return

^!X:: ;This assigns the hotkey CTRL + ALT + X to run the routine
gosub, ARoutine
return

Answer 4

You just need to declare the variable as global inside your function

supposedlyGlobalVariable := "blah"

ARoutine()
{
   global supposedlyGlobalVariable
   localVariable := "asdf"
   MsgBox, The global variable value is %supposedlyGlobalVariable%.  The local variable 
value is %localVariable%.
}


^!X:: ;This assigns the hotkey CTRL + ALT + X to run the routine
ARoutine()
return