Global vs Local

[nitekram]

I had thought I knew the difference, but on showing an example, I found that I could be wrong. Can someone tell me, if I am mistaken, and that a Global variable should be known, even if it is declared in a function?

Local $iVariableOne = 1, $iVariableTwo = 2

If $iVariableOne = $iVariableTwo Then
    MsgBox('', 'see not', 'Hello World! ' & $junk)
    TestFunction()
EndIf


$iVariableTwo = 1
If $iVariableOne = $iVariableTwo Then
    MsgBox('', 'see', 'Hello World!')
    TestFunction()
EndIf

Func TestFunction()


    Global $junk = 666
    For $x = 0 To 10
        ;MsgBox('', '$x = ' & $x, 'Hello World!')
        ConsoleWrite($x & @CRLF)
    Next


EndFunc   ;==>TestFunction

[JohnOne]

In AutoIt3, you can declare a global variable inside a function.

There are many with their personal opinions about that, but whatever they are it does not change the fact.

Edited January 20, 2015 by JohnOne

[nitekram]

I thought that was the case, but if you run my example...it flags it as not being declared, but if I run the function first, as in the example below - it runs, but still get the same warning, If I comment out the call to the function - nothing runs

(4,47) : warning: $junk: possibly used before declaration.
    MsgBox('', 'see not', 'Hello World! ' & $junk)

TestFunction()

MsgBox('', 'see not', 'Hello World! ' & $junk)



Func TestFunction()


    Global $junk = 666
    For $x = 0 To 10
        ;MsgBox('', '$x = ' & $x, 'Hello World!')
        ConsoleWrite($x & @CRLF)
    Next


EndFunc   ;==>TestFunction

[kylomas]

<snip>

Response in error.

Edited January 20, 2015 by kylomas

[JohnOne]

Warning is just a warning.

[kylomas]

The function has to run to declare the var...move the def out of the func and it will work

edit: spelling

Edited January 20, 2015 by kylomas

[nitekram]

The function has to run to declare the var...move the def out of the func and it will work

edit: spelling

 

I understand that I can do that...but I thought the idea was at run/compile time that the variables would be declared along with the functions, prior to running or compiling, and that would mean I could put a Global anywhere and it would be a known value, if it was declared with a value?

[BrewManNH]

That would be wrong, it's not declared until that part of the script executes. Just because you declare it as a global variable doesn't mean anything until it has been actually declared by running the command that declares it. It's better to always declare your variables before using them. Just because your script may declare it before it's used by calling the function, Au3Check doesn't see that, it just starts scanning from the top of the script to the bottom of it, and it sees that there's a variable called in the Global scope that hasn't been declared in the lines preceeding that use.

[guinness]

Be careful too with that empty param as the first message box param. I wish AuroIt had exceptions, so users wouldn't write such terrible code and pay attention to the help file.

[jdelaney]

You have to do things in order...

Local $iVariableOne = 1, $iVariableTwo = 2

Func TestFunction()
    Global $junk = 666
    For $x = 0 To 10
        ;MsgBox('', '$x = ' & $x, 'Hello World!')
        ConsoleWrite($x & @CRLF)
    Next
EndFunc   ;==>TestFunction

If $iVariableOne = $iVariableTwo Then
    TestFunction()
    MsgBox('', 'see not', 'Hello World! ' & $junk)
EndIf

$iVariableTwo = 1
If $iVariableOne = $iVariableTwo Then
    MsgBox('', 'see', 'Hello World!')
    TestFunction()
EndIf

Although this is 'lipstick on a pig'

Edited January 20, 2015 by jdelaney

[guinness]

What happens when you forget down the line that you mistakenly declared a Global variable inside a function? BrewManNH, Melba23, czardas and I don't say the whole declare global variables at the top of the script because we love to waste our breath. We're saving you time debugging fatal errors that can occur in the future when you've forgotten about your script's structure.

[nitekram]

Be careful too with that empty param as the first message box param. I wish AuroIt had exceptions, so users wouldn't write such terrible code and pay attention to the help file.

 

I use msgbox() and consolewrite() for debugging, but when I use msgbox(), I always put an empty param in, unless I plan on using it as way of getting feedback from the end user, then I use 4 as the first parameter - now that might be wrong, but it is a lot easier remembering the number 4 then the constant name.

[nitekram]

What happens when you forget down the line that you mistakenly declared a Global variable inside a function? BrewManNH, Melba23, czardas and I don't say the whole declare global variables at the top of the script because we love to waste our breath. We're saving you time debugging fatal errors that can occur in the future when you've forgotten about your script's structure.

I do not normally put global variables inside of functions, I make them local, and I call it with a global variables. I was giving a basic instruction to a coworker, and when I started changing my example around to show him how global variables worked, it broke.

But I am still glad I brought up this subject, as I really did not know it mattered. I will have to go through all my code, just to make sure I never used a global inside a function. I remember most of the time, I just declare it right before the function - I know I have bad habits lol?

 

EDIT and thanks for everyone's time, again

Edited January 20, 2015 by nitekram

[guinness]

I do not normally put global variables inside of functions, I make them local, and I call it with a global variables. 

I don't quite understand your last point, but I do your first, so great.

We all have bad habits, the thing you should do and we all should do is to learn from them and from others. I am learning new techniques everyday and though it's not necessarily through this Forum, it is on other sites. I just relay this information back, hoping someone will benefit from it.

Edited January 20, 2015 by guinness

[nitekram]

Sorry.

I do not declare global variables in functions. I was only doing it to show an example to a coworker. As it turns out it was a poor example, of both bad programming and being lazy not writing a good piece of code to show him.

That being said, I think you are correct about coding, and we all can learn from others. I think we should all strive to learn how to do it right. It takes a lot of practice, but I have found, that after every project I complete, I know the next time I do will better.

Thanks again for everyone's help

Edit, cleared it ?

Edited January 20, 2015 by nitekram

[guinness]

What did you mean previously by you make local and call it by global variables? Do you have an example so I can possibly understand? Thanks, as maybe I will learn a new technique.

[nitekram]

I am sorry...I think I am a confused writer. What that means is simply, I use local variables inside of functions. What is confusing is the second part. I call the functions, with what ever is needed, being global variables or local variables from another function.