Question about #include-once

[IAMK]

I was wondering why #include-once is an option. It would be good if it was the default setting.

All I see in the help file is:

It is not recommended to add a #include-once line to scripts which are not intended to be used as include files within other scripts.

Why is it that bad to have it in scripts which aren't going to be included?

 

Thank you in advance.

[Earthshine]

the help file is really good

It is quite common to have the same "#include <filename.au3>" line in several of the files included included in a script. If the same file were to be included several times, it is quite likely that this would generate a "Duplicate function" or "Cannot redeclare a Const" error. So when writing a script intended for use as an include file, add #include-once to prevent that file from being included more than once. Note that the #include-once line must be placed at the top of the script and before any other #include lines.
 

regarding that last line, I think it means, if you don't intend to include the au3 file in anything, don't add that to the top. I use the include-once to make my udfs global to the main script. you can use the udfs everywhere then, and only include once overall and logically (all you need is one instance). log4a.au3 logger is like that as well as my WaitForControls.au3

 

it's most likely the way the compiler deals with include files--I can't tell, can't see source.

Edited December 20, 2018 by Earthshine

[BrewManNH]

7 hours ago, IAMK said:

I was wondering why #include-once is an option. It would be good if it was the default setting.

The directive exists  because as explained above, you can't add the same functions to a script or you'll get errors.

N.B. - The below is just conjecture:

The reason it's not the default is because it probably adds overhead to the interpreter at run time or compiling time to have it try and determine whether the file has already been included once before. And you don't use it in a script that's not an include for that reason. It probably has to check every file name included every time the script is run or compiled. And by script I mean an uncompiled script being run by the AutoIt3.exe program.

[IAMK]

@Earthshine I have 2 types of scripts:
1- AutoIT_Name.au3
2- AutoIT_Func_Name.au3
Scripts with Func in the name are never compiled, and are only there to be included by other scripts, and to ensure there are no duplicate definition errors, I use #include-once in them. The scripts without Func in the name are never included, so there is no reason for me to use #include-once.
However, I still don't see why #include-once isn't made the default, as it doesn't seem too harmful to have it in all of my scripts.

@BrewManNH Yes, so I assumed that the overhead would just be that the compiler checks other files which include it.
With that being said, I can't see that taking more than milliseconds, and it's only done once for each file used (before turning the script into a single .exe which won't have to ever check this again).

[BrewManNH]

Feel free to do it how you'd like, there's nothing holding you back from using it. It's just not the default because it doesn't need to be. Putting unnecessary directives into a script like this one won't break anything, just adds to the overhead and unneeded typing.