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icu

Syntax error when using ByRef ???

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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

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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.

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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

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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.

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My contribution to others projects or UDF based on  others projects: * _sql.au3 UDF  * POP3.au3 UDF *  RTF Printer - UDF * XML.au3 UDF * ADO.au3 UDF SMTP Mailer UDF * Dual Monitor resolution detection *

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I encourage you to read: * Global Vars * Best Coding Practices * Please explain code used in Help file for several File functions * OOP-like approach in AutoIt * UDF-Spec Questions *  EXAMPLE: How To Catch ConsoleWrite() output to a file or to CMD *

"Homo sum; humani nil a me alienum puto" - Publius Terentius Afer
"Program are meant to be read by humans and only incidentally for computers and execute" - Donald Knuth, "The Art of Computer Programming"
:naughty:  :ranting:, be  :) and       \\//_.

Anticipating Errors :  "Any program that accepts data from a user must include code to validate that data before sending it to the data store. You cannot rely on the data store, ...., or even your programming language to notify you of problems. You must check every byte entered by your users, making sure that data is the correct type for its field and that required fields are not empty."

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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.

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mLipok
I'm glad I could help
greetings
mlipok

Signature beginning:   Wondering who uses AutoIT and what it can be used for ?
* GHAPI UDF - modest begining - comunication with GitHub REST API Forum Rules *
ADO.au3 UDF     POP3.au3 UDF     XML.au3 UDF    How to use IE.au3  UDF with  AutoIt v3.3.14.x  for other useful stuff click the following button

Spoiler

Any of my own code posted anywhere on the forum is available for use by others without any restriction of any kind. 

My contribution (my own projects): * Debenu Quick PDF Library - UDF * Debenu PDF Viewer SDK - UDF * Acrobat Reader - ActiveX Viewer * UDF for PDFCreator v1.x.x * XZip - UDF * AppCompatFlags UDF * CrowdinAPI UDF * _WinMergeCompare2Files() * _JavaExceptionAdd() * _IsBeta() * Writing DPI Awareness App - workaround * _AutoIt_RequiredVersion() * Chilkatsoft.au3 UDF * TeamViewer.au3 UDF * JavaManagement UDF * VIES over SOAP * WinSCP UDF * GHAPI UDF - modest begining - comunication with GitHub REST APIErrorLog.au3 UDF - A logging Library
 

My contribution to others projects or UDF based on  others projects: * _sql.au3 UDF  * POP3.au3 UDF *  RTF Printer - UDF * XML.au3 UDF * ADO.au3 UDF SMTP Mailer UDF * Dual Monitor resolution detection *

Useful links: * Forum Rules * Forum etiquette *  Forum Information and FAQs * How to post code on the forum * AutoIt Online Documentation * AutoIt Online Beta Documentation * SciTE4AutoIt3 getting started * Convert text blocks to AutoIt code * Games made in Autoit * Programming related sites * Polish AutoIt Tutorial * DllCall Code Generator * 

Wiki: Expand your knowledge - AutoIt Wiki * Collection of User Defined Functions * How to use HelpFile * Good coding practices in AutoIt * 

IE Related:  * How to use IE.au3  UDF with  AutoIt v3.3.14.x * Why isn't Autoit able to click a Javascript Dialog? * Clicking javascript button with no ID * IE document >> save as MHT file * IETab Switcher (by LarsJ ) * HTML Entities * _IEquerySelectorAll() (by uncommon) * IE in TaskScheduler

I encourage you to read: * Global Vars * Best Coding Practices * Please explain code used in Help file for several File functions * OOP-like approach in AutoIt * UDF-Spec Questions *  EXAMPLE: How To Catch ConsoleWrite() output to a file or to CMD *

"Homo sum; humani nil a me alienum puto" - Publius Terentius Afer
"Program are meant to be read by humans and only incidentally for computers and execute" - Donald Knuth, "The Art of Computer Programming"
:naughty:  :ranting:, be  :) and       \\//_.

Anticipating Errors :  "Any program that accepts data from a user must include code to validate that data before sending it to the data store. You cannot rely on the data store, ...., or even your programming language to notify you of problems. You must check every byte entered by your users, making sure that data is the correct type for its field and that required fields are not empty."

Signature last update: 2018-10-15

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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.

  • Like 1

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eMyvnE

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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.


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