What do you mean "cannot use parentheses?"

RE: What do you mean "cannot use parentheses?"

Deadprogrammer — Wed, 17 Sep 2003 01:39:00 GMT

For some time I had a printout from your 1999 usenet post about this taped to my wall. Now it occupies a place of honor in my snippet database. Thank you so much for it.

RE: What do you mean "cannot use parentheses?"

Eric Lippert — Wed, 17 Sep 2003 02:24:00 GMT

I live to serve!

In, Out, In-Out, Make Up Your Mind Already

Fabulous Adventures In Coding — Thu, 19 Feb 2004 04:54:00 GMT

I was talking about reference types vs. by-reference variables a while back. Recall that both JScript and VBScript have reference types (ie, objects) but JScript does not have by-reference variables. COM supports passing variable references around, but unfortunately the intersection of early-bound COM and late-bound IDispatch is a little bit goofy.

re: Aaargh, Part Six: One More Thing About Comments

Fabulous Adventures In Coding — Thu, 06 May 2004 19:44:00 GMT

re: Aaargh, Part Six: One More Thing About Comments

Fabulous Adventures In Coding — Thu, 06 May 2004 19:50:00 GMT

re: Aaargh, Part Six: One More Thing About Comments

Fabulous Adventures In Coding — Thu, 06 May 2004 20:05:00 GMT

More On ByRef vs ByVal

Fabulous Adventures In Coding — Thu, 06 May 2004 20:08:00 GMT

It occurs to me that there may be some confusion about what exactly

One More Problem Found

Curtis — Wed, 25 May 2005 12:35:24 GMT

DUDE ! YOU Fn ROCK !
This document is more informative than the MSDN library on this subject.
I was banging my head against the wall with this same problem for hours. I had 2 arguments and was calling a sub from an onClick and was getting the error At lines 511-513. 8 pages with the same code.

OK, I have one more Addition to your List of things that will cause the error.

after I fixed all 8 pages with this... they all started working, no errors. HOWEVER, the main page (default.asp) that DID previously work, was now giving the same error. I could not finger out the problem, hacked out code chunk by chunk... I mean... I ALREADY fixed it... there must be something else I missed.

after about 20 minutes I realized that the only difference on the main page was that at the very top in the <BODY> tag I was doing an onLoad="subLoadDefaults()" none of the other pages had that.

WITH the fixed code, that now triggered the errors way down in lines 511- 513....
now, the funny part is, that before when I had the code WRONG in those same lines, they worked quite fine and no errors. Somehow the onLoad="subLoadDefaults()" made the rest of the page ignore that it was wrong.

I got rid of the onLoad all together and the page works fine now.

THANKS !!!!

re: What do you mean "cannot use parentheses?"

Eric Lippert — Wed, 25 May 2005 20:51:01 GMT

Dude! As I said earlier, I live to serve!

I'm not sure why your onload guy was causing a problem -- I'd have to actually see the server code in action to figure it out. But I'm glad you've managed to sort out your problem.

re: What do you mean "cannot use parentheses?"

Jan Lourens — Thu, 21 Jul 2005 10:50:04 GMT

Eric, you are a friggin' legend! I can't thank you enough for clearing that up for me - been looking like a fool in front of new collueges for hours until I stumbled upon this site.

Thanks.

re: What do you mean "cannot use parentheses?"

Aaron — Tue, 09 Aug 2005 23:45:58 GMT

Thanks Eric, I know for certain I 'learned' this quite some time ago, and you have taught me once again.

re: What do you mean "cannot use parentheses?"

anon — Tue, 10 Jan 2006 02:07:19 GMT

Another stupid thing that will trigger this error: using

DateDiff("n", Date1, Date2)

by itself (not with Response.Write or assigning it to a variable)

re: What do you mean "cannot use parentheses?"

Clinton — Tue, 18 Apr 2006 11:47:41 GMT

I can not beleive that it was that simple yet I had stewed over this for ages! Mate the lights just went on and a big thank you to you.

re: What do you mean "cannot use parentheses?"

Martin — Wed, 28 Jun 2006 21:32:49 GMT

That is the greatest piece of knowledge about sub/function parameters.

Just one question: Does this byref/byval parens apply as well in VB6 and VBA in which you can actually declared subs and functions by using the byref and byval keywords for parameters? If it applies, does it overrides default behavior and/or coded behavior?

re: What do you mean "cannot use parentheses?"

Eric Lippert — Wed, 28 Jun 2006 23:21:06 GMT

Yes, the syntax is the same for VB6/VBA. The VBScript syntax and semantics were designed for compatibility with VB6.

re: What do you mean "cannot use parentheses?"

Visakh — Sun, 26 Nov 2006 08:27:28 GMT

Hi Eric,

Thanks a lot for the article. This error was bugging me for an hour!!! I am calling VBS function inside JSTL and i thot it was mixing of scripts which caused the issue. Does this mean, i have to split the 2 behaviors into 2 functions, if i have to call the Sub with 2 parameters?

Regards

Visakh

re: What do you mean "cannot use parentheses?"

Jan Philipp Giel — Mon, 11 Dec 2006 13:17:50 GMT

I am a bit confused right now.

In your newsgroup posting (1) you say

n = Foo((z)) ' legal, passes z by reference

and in your blog it is "to pass x byval"

z = f((x))

I guess "by value" is the right one?

(1) http://www.mvps.org/scripting/languages/eric_lippert_parens_in_procedures.txt

Information on calling VBS functions

Weblog — Tue, 12 Dec 2006 23:47:28 GMT

Taken from: http://blogs.msdn.com/ericlippert/archive/2003/09/15/52996.aspx What do you mean "cannot

re: What do you mean "cannot use parentheses?"

Eric Lippert — Wed, 13 Dec 2006 00:07:10 GMT

Jan: yes, the newsgroup posting has a typo. I regret the error.

re: What do you mean "cannot use parentheses?"

NikitaP — Mon, 12 Feb 2007 22:26:48 GMT

Just add "Call " before you function call. Worked for me.

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re: What do you mean "cannot use parentheses?"

vm — Sat, 12 May 2007 01:35:28 GMT

kind of relevant.. the error could happen if you don't include javascript: tag before a javascript function call on a page having both vbscript and javascript.

メモ: サンプル、 PowerShell, etc... (VBScript)

システム管理な雑記 -- Sleeve notes of a sysadmin -- — Fri, 01 Jun 2007 22:10:20 GMT

メモ: サンプル、 PowerShell, etc... (VBScript)

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メモ: サンプル、 PowerShell, etc... (VBScript)

re: What do you mean "cannot use parentheses?"

k0nvikt — Wed, 13 Jun 2007 11:55:07 GMT

Can you then tell me how do you call a sub when an error occurs in vbs

Tried :"On Error mySub()" did'nt work

re: What do you mean "cannot use parentheses?"

Eric Lippert — Wed, 13 Jun 2007 19:23:23 GMT

VBScript only supports "On Error Resume Next" for error handling, sorry.

re: What do you mean "cannot use parentheses?"

DrewGuy — Tue, 21 Aug 2007 20:21:29 GMT

Hey, I just wanted to thank you. I'm incredibly new to VB of any kind, and your site provided the answer after a couple hours of struggling with this problem. You rock!

re: What do you mean "cannot use parentheses?"

san — Fri, 14 Sep 2007 19:42:05 GMT

why am i getting this error while trying to set a response.status and response.addheader

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re: What do you mean "cannot use parentheses?"

Beez — Fri, 05 Oct 2007 01:06:49 GMT

This is evil. I wonder if this is a Basic artifact? I hated this and just spent an afternoon trying to figure out why my subroutine's change to the value of it's parameter did not persist when the subroutine returned *cry*

?????????? ??-VBScript - ?????? 2

?????????? ??-VBScript - ?????? 2 — Sun, 07 Oct 2007 21:37:33 GMT

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re: What do you mean "cannot use parentheses?"

dKes — Wed, 13 Feb 2008 01:16:39 GMT

Hi Eric,

I get the error message above. Here is a part of script - what is wrong?

Set objShell = WScript.CreateObject("WScript.Shell")

objShell.Run ("ftp -s:" & chr(34) & strFTPScriptFileName & chr(34), , True)

dKes

re: What do you mean "cannot use parentheses?"

JAaronAnderson.com — Mon, 03 Mar 2008 22:12:14 GMT

the examples of "to pass x byref, y byref: " and others do not make sense to me? Please help me understand...

thx

re: What do you mean "cannot use parentheses?"

Eric Lippert — Mon, 03 Mar 2008 22:17:52 GMT

I wrote an article about that a mere six hours after I wrote the article above! :-)

http://blogs.msdn.com/ericlippert/archive/2003/09/15/53005.aspx

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re: What do you mean "cannot use parentheses?"

SD — Wed, 14 May 2008 20:58:23 GMT

Great explanation. Thank you!!!

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re: What do you mean "cannot use parentheses?"

Randy — Thu, 29 Jan 2009 05:45:27 GMT

Eric,

Great post.

I have the following in a file show.vbs:

Sub Show()

MsgBox "Show"

End Sub

call Show()

call Show

Show()

Show

All of these invocations seem to work. I would have thought that two of these would be incorrect. Or is there something I'm missing with the no arguments scenario? e.g. in VBA if you were to try Show() it would tell you that "Expected: =" which makes sense under 3.1 -- VBA sees the parentheses and assumes that the call should be a Function so there should be an assignment.

Thanks.

re: What do you mean "cannot use parentheses?"

Al Dunbar — Fri, 08 May 2009 03:42:04 GMT

show(a) does not error out, however it may not do exactly as you'd expect for the reasons given long ago by Eric. Anyway, I'm not surprised that none of the four examples above errors out, as I see the issue mainly showing up when the number of arguments is greater than one.

re: What do you mean "cannot use parentheses?"

I talk to VBscript — Thu, 11 Jun 2009 10:11:37 GMT

I read your explaination once and didnt understand it.

i tried it out and nothing worked.

I read it again and swore at the screen severl times and still nothing worked.

I read it again and tried it again and swore a lot more and then started talking to my reflection in the screen and things started to work.

I owe you beer for the good of my mental health.

re: What do you mean "cannot use parentheses?"

all — Tue, 01 Dec 2009 05:51:11 GMT

how to write this?

Set WshShell = WScript.CreateObject("WScript.Shell")

WshShell.Run(iexplore -k http://support.microsoft.com/kb/154780, 1, true)

re: What do you mean "cannot use parentheses?"

JoeNo1 — Fri, 04 Dec 2009 23:21:58 GMT

This has been always confusing for me. Here, I find a perfect answer.

Thank you so much, Eric.

Joe

re: What do you mean "cannot use parentheses?"

BigJeff5 — Mon, 07 Dec 2009 18:26:33 GMT

>all said:

>how to write this?

>Set WshShell = WScript.CreateObject("WScript.Shell")

>WshShell.Run(iexplore -k http://support.microsoft.com/kb/154780, 1, true)

You should use quotation marks around the command, first off. That wasn't the cause of your problem but it would likely just cause another error after you fixed the parenthesis error.

There are two ways to correctly call the function, you can either preface the function with "Call" like this:

Call WshShell.Run("iexplore -k http://support.microsoft.com/kb/154780", 1, true)

Or you can simply remove the parenthises:

WshShell.Run "iexplore -k http://support.microsoft.com/kb/154780", 1, true

This is because, as Eric explained in his article, VBSCRIPT sees the parenthesis in function(myarg) as telling it to pass myarg by reference instead of by value. It does NOT see the parenthesis as describing where the list of arguments start and end. Since the comma tells VBSCRIPT where the next argument is, and it is expecting a parenthesis before the comma, it puts two and two together and tells you you can't use parenthesis (around the list of arguments) when calling a sub.

If it's still confusing to you, then just remember to allways use "Call" before calling a subroutine and it will behave the way you expect it to, because Call does require all arguments to be within a set of parenthesis. You can wrap individual arguments in the parenthesis to set them to by reference instead of by value.