Variable scopes - Test script

[Unsigned]

I wrote this up real quick to sort out some questions I had about AutoIt's variable scope. Did you know For loops within functions cannot use a Global as the iterator variable? I didn't.

Posting it here in case it can enlighten anybody else. It runs several tests, displaying the results of each test individually.

expandcollapse popup

MsgBox(0, "Info", "global scope is when execution is NOT inside a function." & @CR & "local scope is any time execution IS inside a function.")
 
Global $globalglobal = 2
Func GlobalFunc1($value)
Local $globalglobal = $value
EndFunc
GlobalFunc1(10)
AssertError("'Local' in local scope will create a 'Local'", $globalglobal <> 2)
 
Global $globalset = 2
Func GlobalFunc2($value)
Global $globalset = $value
EndFunc
GlobalFunc2(10)
AssertError("'Global' in local scope creates/accesses a 'Global'", $globalset <> 10)
 
Dim $dimglobal = 2
Local $globallocal = 2
Func LocalGlobalFunc($value)
$dimglobal = $value
$globallocal = $value
EndFunc
LocalGlobalFunc(10)
AssertError("'Dim' or 'Local' in global scope will always create 'Global' anyway", ($dimglobal <> 10) Or ($globallocal <> 10))
 
For $globalindex = 1 to 4 ; $globalindex will be created as a Global
Local $junk = "something"
Next
Global $lastglobalindex = $globalindex
Func GlobalLoop1($value)
Global $globalindex
$globalindex += $value
EndFunc
GlobalLoop1(99)
AssertError("loop indexes in global scope are always 'Global'", $globalindex <> ($lastglobalindex + 99))
 
Global $globalloop = 99
Func LoopFunc($last)
Global $globalloop ; This declaration should have no effect on the loop variable below
Local $firstgloballoop = $globalloop
For $globalloop = 1 to $last ; The index variable here will be Local notwithstanding our previous attempt to make it reference the existing Global
  Local $blah = "something"
Next
Local $retarray[2]
$retarray[0] = $firstgloballoop
$retarray[1] = $globalloop
Return $retarray
EndFunc
Global $theretarray = LoopFunc(3)
AssertError("loop indexes in local scope will always be 'Local', even to the point of ignoring/overriding any prior 'Global' declarations", ($theretarray[0] <> 99) Or ($theretarray[1] <> 4))
 
Global $array[10]
$array[0] = "hi"
Func ArrayFunc($value)
Dim $array[5]
$array[0] = $value
EndFunc
ArrayFunc("lol")
AssertError("'Dim' in local scope will use a pre-existing 'Global' if it exists, otherwise create a 'Local'", $array[0] <> "lol")
 
MsgBox(0, "Done", "Thats the end of the tests!")
Exit
 
 
; Used to display test results only
Func AssertError($name, $bool)
If $bool Then Return MsgBox(16, "Test Results", '' & $name & ' = FAIL')
Return MsgBox(64, "Test Results", '' & $name & ' = SUCCESS')
EndFunc

[Melba23]

UCL,

Did you know For loops within functions cannot use a Global as the iterator variable? I didn't

Then you should have read the Help file more carefully:

For...To...Step...Next
 
variable - The variable used for the count.
 
Remarks
The Variable will be created automatically with a LOCAL scope, even when MustDeclareVars is on.

And why would you want the actual count variable to be Global anyway - you reset it each time you start the loop! You can of course use a Global variable as the Start or Stop value - which actually serves a useful purpose.

Have you read the Variables - using Global, Local and ByRef tutorial in the Wiki - it explains scope in some detail.

M23

[AdmiralAlkex]

Also don't use Dim. Use Local or Global so you know where things are.

[Unsigned]

Then you should have read the Help file more carefully:

Haha Barring some dramatically new syntax, I don't usually read exhaustively on every basic construct for a new language. (After all, most languages out there (that I use regularly) fall into two categories, C-like and BASIC-like.)

Good to know that it's in the manual though! I just found the script useful to illustrate the behavior (a little code can be faster than searching the manual sometimes )

Edited September 29, 2011 by Unsigned