ID: 41228 Updated by: [EMAIL PROTECTED] Reported By: terminatorul at gmail dot com Status: Open Bug Type: Documentation problem PHP Version: Irrelevant New Comment:
My point was that the term "short-circuit" is already mentioned twice on the page, if you didn't know what it meant in this context then a google search for "short-circuit operator" would yield a page full of relevant results. Of course it could be spelled out in the text, but even if I was in favour of doing so, I don't have phpdoc karma. That's why I just stated my opinion and left the bug open. Previous Comments: ------------------------------------------------------------------------ [2007-04-30 11:50:08] terminatorul at gmail dot com My point exactly. A programing language may or may not guarantee side-effects from evaluation of operands to logical operators. Or at least would say that it is undefined if the side-effect occurs. The proffesional C++ programmer will find it normal for the language to shortcut the expression, while a beginner will not understand what's wrong with his/her code. ------------------------------------------------------------------------ [2007-04-30 11:44:35] [EMAIL PROTECTED] Good ole MS! http://support.microsoft.com/kb/817250 ------------------------------------------------------------------------ [2007-04-30 11:42:27] [EMAIL PROTECTED] Two opposing thoughts. Delphi - http://info.borland.com/techpubs/delphi/delphi5/oplg/syntlmnt.html#10548 In Delphi, shortcut/short-circuit is optional, though as standard it is enabled. VB - http://www.informit.com/guides/content.asp?g=dotnet&seqNum=480&rl=1 Seemingly VB does NOT have a short circuit. Who do you believe. For the seasoned programmer, this is perfectly obvious. But if you're upgrading your skill set from, say, VB, then this REALLY odd behaviour is completely new. And what debugging would you provide? This should be documented and probably in several places as there are many references to boolean logic throughout the manual. It is the LACK of documentation on this standard feature within PHP that is the issue. ------------------------------------------------------------------------ [2007-04-30 10:08:31] [EMAIL PROTECTED] This isn't a side-effect, but an intrinsic property of these operators. As two out of the four user notes on the page mention, the first dating back to 1999, these operators short-circuit. Perhaps this could be explained in the text to make it clearer for people new to programming, but I don't think there's any great need; I assume most people can look up terms they're not familiar with. ------------------------------------------------------------------------ [2007-04-30 09:00:14] [EMAIL PROTECTED] Agreed. <?php // Echo's F and does NOT set $a. echo (False && ($a=1)) ? 'T' : 'F'; // Echo's T, sets $b but does not set $c. echo (($b=2) || False || ($c=3)) ? 'T':'F'; // Turn off notices about undefined variables for $a and $c. error_reporting(E_ALL & ~E_NOTICE); // Rather than "1 2 3", we get just " 2 ". echo "$a $b $c"; ?> ------------------------------------------------------------------------ The remainder of the comments for this report are too long. To view the rest of the comments, please view the bug report online at http://bugs.php.net/41228 -- Edit this bug report at http://bugs.php.net/?id=41228&edit=1
