Global Vars

[Valik]

Variables should always be declared in the smallest scope possible in any language (for languages that support it). For example, don't front-load your functions with all the variable declarations. Declare variables right before they are used. If a variable doesn't need to exist in global scope then use it in local scope. Prefer function return values and function parameters to pass data around rather than global variables. Keep variables in existence no more than necessary.

[Mat]

Contradictory to the UDF standards! But I presume that is more for readability, and writing more structured code.

All variables must be declared at the beginning of the UDF with a “Local” scope and before they are used for the first time.

Also, my original question was one of lots of locals vs. a few globals. With a GUI in message loop mode, the local variables will have to exist until the GUI is closed. With OnEvent mode, the same will apply to a few globals. Given what you have just said, message-loop mode should be used in preference to OnEvent due to the use of locals rather than globals.

[Valik]

Contradictory to the UDF standards! But I presume that is more for readability, and writing more structured code.

I didn't write that nor have I wrote very many UDFs. I do not agree with a lot of things the UDFs do.

Also, my original question was one of lots of locals vs. a few globals. With a GUI in message loop mode, the local variables will have to exist until the GUI is closed. With OnEvent mode, the same will apply to a few globals. Given what you have just said, message-loop mode should be used in preference to OnEvent due to the use of locals rather than globals.

You do not understand what I am saying if you think that. You're seemingly looking for some blanket rule to apply in all situations. That rule does not exist. Whether you use events or a message loop is up to you and the needs of the application you are writing. My statements apply for either mode because my statements are not related to any mode (in fact my statements aren't related to any language in particular, either).

[Mat]

You do not understand what I am saying if you think that. You're seemingly looking for some blanket rule to apply in all situations. That rule does not exist. Whether you use events or a message loop is up to you and the needs of the application you are writing. My statements apply for either mode because my statements are not related to any mode (in fact my statements aren't related to any language in particular, either).

Ok, that sort of answers it anyway. I will contend the fact that the scopes are related to the mode. Message-loops need lots of variables within a single function and OnEvent requires no variables, but in reality you will need to use a few globals for the parent window etc. Granted they can exist in either, and it's fairly trivial anyhow, but i'm fairly sure you'll agree with me on that point.

[Melba23]

Valik,

Thank you for taking the time to post so often in this topic. As a mere hobbyist coder I have found it most interesting to hear the views of a serious programmer and I shall certainly bear your points in mind when I start my next project.

M23

[Beege]

This topic has been very educational. I am also a mere hobbyist who likes learning these kind of "undocumented" things. Its now got me wondering, are global constants just as bad? I'm telling myself no because there is a ton when it comes to the udfs, but I dont know.

Edit: Looking back, I think this was the dumbest question I have ever asked.

Edited October 1, 2011 by Beege

[Blue_Drache]

I just have a question about form. With all due respect to previous posters, I am curious about declaring global variables within a UDF.

For example:

; start program
#include block
GlobalInit()
; rest of code

; end of code

; begin user defined functions
Function GlobalInit()
  Global $a
  Global $b
  Global $c
End Func

Would this be considered bad form from a programming point of view?

Or would it just be bad programming?

Edited July 5, 2010 by Blue_Drache

[MvGulik]

whatever Edited February 7, 2011 by MvGulik

[Melba23]

Blue_Drache,

Declaring Global variables in a UDF is something to avoid if you can - but it is often unavoidable.

I just declare them at the beginning of the UDF, making sure I use a unique name to prevent accidental overwriting by the user.

I would certainly not do what you suggest. Why call a function - just declare the variables as normal. Remember that #include inserts the text of the named file at that point in your script, so you would get something like this:

; Your_UDF.au3

Global $a, $b, $c
; followed by UDF code

; ----------------

; Your script

#include "Your_UDF.au3"
; followed by your script code

; ----------------

; Which when expanded will give you 

Global $a, $b, $c
; followed by UDF code
; followed by your script code

Your Global variables are now declared at the beginning of your script as you would wish.

M23

[Blue_Drache]

Then it is "Bad programming". I was looking for a more elegant appearing solution than an include file, honestly. Thank you though. *smacks forehead* #Region is exactly what I needed. Sorry to have bothered.

*wanders off muttering about how handy help files can be*

Edited July 7, 2010 by Blue_Drache

[mLipok]

Nice reading.