iif() stack overflow exception "problem"? - KiXtart.org - official site

You are not logged in. [Log In] KiXtart.org website » Forums » KiXtart » Beta » iif() stack overflow exception "problem"?

Page 2 of 2

2

Topic Options

#79399 - 2003-01-08 11:59 PM Re: iif() stack overflow exception "problem"?
Lee Wilmott Lee Wilmott Starting to like KiXtart Registered: 2002-09-17 Posts: 106 Loc: Bristol, UK	The If ... Else ... statement may well be quicker; I was just thinking (maybe that's the problem) that my exp() function would be a good test for the new iif() function. You know what it is like, a new function is introduced to KiX - you've gotta have a look, haven't you?!?!? Like you Shawn, I would only use iif() for the more simplistic task. However, the reason for posting my original post is that I thought that the returned result was incorrect and that it may have bigger, more important consequences. I must admit, I'm not sure that after reading your comments that this is any clearer for me!!! I agree with you Shawn, the iif() function is merely... code: Function IIF($x,$y,$z) If $x $IIF=$y Else $IIF=$z EndIf EndFunction But seeing as this is all my exp() function contains is the if ... else ... statement, so why can't this statement be replaced with iif()? Although, I believe you are correct; logically speaking this is exactly what iif() does, however programatically I would have to argue that it is different! Am I missing something? Lee
Top

#79400 - 2003-01-09 12:11 AM Re: iif() stack overflow exception "problem"?
Lonkero Lonkero KiX Master Guru Registered: 2001-06-05 Posts: 22346 Loc: OK	you can replace. but as you put a function into the parameter, it will be scanned before the iif is tested. for shawns example: code: $x = iif(1=1,FuncOne(),FuncTwo()) function FuncOne() ?"FuncOne..." endfunction function FuncTwo() ?"FuncTwo..." endfunction it is translated to: code: $x = iif(1=1,?"FuncOne...",?"FuncTwo...") and then executed. say you have nested function which calls itself like you had. I'm sure what it becomes. it keeps adding itself to the parameters until the stack gets filled. like you probably know, expressions are executed in bracket-style manner. this is different with commands. command does something and if is conditional command. mmm... to make iif-function work as "expected", ruud would need to override normal syntax rules for it. making any sense? _________________________ ! download KiXnet
Top

#79401 - 2003-01-09 09:39 AM Re: iif() stack overflow exception "problem"?
Lee Wilmott Lee Wilmott Starting to like KiXtart Registered: 2002-09-17 Posts: 106 Loc: Bristol, UK	I'm with you! Sorry...It was late last night when I posted my last message! "Speak" soon, Lee
Top

#79402 - 2003-01-09 05:55 PM Re: iif() stack overflow exception "problem"?
Anonymous Anonymous Unregistered	First of all, let me say that I was really excited to see the true community-power at work in this thread. The initial post was intriguing, and your combined responses have produced the exact cause and appropriate work arounds. Makes me feel proud to be part of this community! And, as a result of your efforts, my response can be short: the phenomenon is indeed caused by the fact that all parameters of a function are always evaluated. Changing this behaviour would be non-trivial, and might break downward compatibility. Basically, IIF() is just a bit of 'syntactical candy' which can make certain scripts shorter. If readability and performance are your main concern, good old IF is probably a better choice. Thanks to all the participants, and keep scripting! Ruud
Top

#79403 - 2003-01-09 06:11 PM Re: iif() stack overflow exception "problem"?
Sealeopard Sealeopard KiX Master Registered: 2001-04-25 Posts: 11164 Loc: Boston, MA, USA	So, basically code: $a=10 if $a<10 $b='a is smaller than 10' else $b='a is not smaller than 10' endif could be a candidate for the IIF as in code: $a=10 $b=iif($a<10,'a is smaller than 10','a is not smaller than 10') but anything involving more complicated things like function evaluations would be off-limits. You might need to update the Manual to make this clear. [ 09. January 2003, 18:14: Message edited by: sealeopard ] _________________________ There are two types of vessels, submarines and targets.
Top

#79404 - 2003-01-10 10:16 AM Re: iif() stack overflow exception "problem"?
Richard H. Richard H. Administrator Registered: 2000-01-24 Posts: 4946 Loc: Leatherhead, Surrey, UK	Agreed, the manual should explicitly state the situations in which IIF() should be used, and the pitfalls of having the expressions always evaluated. It caught me out at first as coming from a mainly 'C' background I am used to the ternary "?:" operator which appears to work in a similar way. The form is: quote: (condition) ? (True-expression) : (False-expression); The difference is that this is a language construct, and only the expression which corresponds to the result of the condition expression is evaluated. The fact that IIF() is a function implies that the parameters must be evaluated first, but it will save some headaches if it is spelled out explicitly in the documentation.
Top

#79405 - 2003-01-11 12:34 AM Re: iif() stack overflow exception "problem"?
Lonkero Lonkero KiX Master Guru Registered: 2001-06-05 Posts: 22346 Loc: OK	can't say that I agree. there is no place I've found that it's better to use iif. mainly because I want to run stuff by speed. there is no place where I would recommend it. anyway, about adding some words to the manual to clarify that the parameters are eveluated will decrease the confusion. _________________________ ! download KiXnet
Top

#79406 - 2003-01-10 04:24 PM Re: iif() stack overflow exception "problem"?
Sealeopard Sealeopard KiX Master Registered: 2001-04-25 Posts: 11164 Loc: Boston, MA, USA	The only place in my UDFs where I could see potential use of IIF is to simplify the following type of IF construct: code: ; example if @INWIN=1 $os='Windows NT/2000/XP' else $os='Windows 9x' endif ; replaced example $os=IIF(@INWIN=1,'Windows NT/2000/XP','Windows 9x') and similar plain value-assigning IF constructs. _________________________ There are two types of vessels, submarines and targets.
Top

#79407 - 2003-01-10 04:28 PM Re: iif() stack overflow exception "problem"?
Shawn Shawn Administrator Registered: 1999-08-13 Posts: 8611	I think IIF's are ok as long as one fully understands what one is doing - which I didn't - i thought of IIF more along the lines of the tenary IF that Richard outlined. Not the same beast at all.
Top

#79408 - 2003-01-10 04:40 PM Re: iif() stack overflow exception "problem"?
Lee Wilmott Lee Wilmott Starting to like KiXtart Registered: 2002-09-17 Posts: 106 Loc: Bristol, UK	I totally agree with you shawn... quote: IIF's are ok as long as one fully understands what one is doing Using iif() is fine...as long as you understand what it is doing and how it is doing it! Lee
Top

Page 2 of 2

2

Previous Topic

Previous Topic View All Topics

View All Topics

Index Next Topic

Next Topic

Moderator: ShaneEP, Arend_, Jochen, Radimus, Glenn Barnas, Allen, Ruud van Velsen, Mart

Hop to:

Shout Box

Who's Online

0 registered and 628 anonymous users online.

Newest Members

Raoul, Timothy, Jojo67, MaikSimon, kvn317
17875 Registered Users

Generated in 0.064 seconds in which 0.029 seconds were spent on a total of 12 queries. Zlib compression enabled.