Syntax error when using ByRef ???

[icu]

Dear AutoIt Community,

1. I've checked the help .chm file
2. I've searched the AutoIt forum, and
3. I've Googled for a solution.

No luck.

I'm writing a UDF and I don't understand why SciTE Version 3.3.0 (Mar 30 2013 17:50:01) is giving me a syntax error on this line of code:

Func _iStep(ByRef $iFlag = 0)

 

I've also tried the following and get the same "ERROR: syntax error" console message in SciTE:

Func _iStep(Const ByRef $iFlag = 0)

 

When I remove the = 0 and just leave the function without a default value like this:

Func _iStep(ByRef $iFlag)

 

Scite does not throw up any syntax error message.

This is a massive pain since I want my UDF to have a default value of 0.  Any help is greatly appreciated.

Many thanks,

icu

[jaberwacky]

Why do you need ByRef?  Is it a string or array to which you wish to write?  Are you wanting to modify more than one variable in one function?  If so then maybe your function is spread too thin trying to do too many things.  If you don't want to write to the variable then leave the ByRef off.  Post your function please so that I or others may provide some guidance.

[Danyfirex]

You can't have a optional parameter with byref.

The ByRef keyword is optional and means: (1) the parameter must a variable, and (2) the original variable is linked to the parameter, so that any changes to the parameter inside the function, would affect the original variable as well. By default, a parameter is passed by value which means that a copy of the parameter's value, is manipulated by the function.

by GaryFrost

saludos

[mLipok]

The reason is simple

if you use ByRef directive, it means that you are going to use a previously defined value.

Previously, ie before the function call.

Which means that they do not need to post the default value in the syntax, because the default value is used only, in case you do not give the value of the parameter in the function call.

 

There is then a contradiction.

Using ByRef essentially excludes the use of default values​​, since deciding to use ByRef function demands that the parameter was defined, so it can not be an optional parameter.

 

You have two choices:

Use ByRef or use the default values​​.

 

In this way, I understand the problem.

However, it is possible that I am wrong.

[icu]

Thank you jaberwocky6669, Danyfirex, mlipok.  I understand now why using ByRef in this way was incorrect.  Thank you again mlipok for your clear answer.

[mLipok]

I'm glad I could help

greetings

mlipok

[trancexx]

It's not all that simple.

You should be able to use default values with Byref. It's only that noone found time to add it to the language. But it was on my todo list.

For example see this:

ABC(23)

Func ABC(ByRef $a)
    $a = 46
EndFunc

...That code is perfectly valid in AutoIt. It's only a bug in Au3Check that wouldn't let you run it, so you have to disable it before running that code.

If that's allowed then using simple logic this:

ABC(23)

Func ABC(ByRef $a = 0)
    $a = 46
EndFunc

... should be allowed too.

It's missing feature.

[BrewManNH]

AutoHotKey supports ByRef parameters with default values for functions, if you don't supply the parameter it ignores the ByRef and creates a local variable.  Might be something worth looking at in AutoIt as well.