Req #52907 [NEW]: "is" operator -- test whether two lvalues are references to each other

From: Operating system: PHP version: Irrelevant Package: Variables related Bug Type: Feature/Change Request Bug description:"is" operator -- test whether two lvalues are references to each other Description: ------------ Currently, PHP has "==", which loosely checks for equality, and "===", which strictly checks for equality. However, for strings and booleans and such, both only test for equality -- there's no way to know (without altering the variable's contents) whether two variables are identical references unless they refer to an object. If PHP allows the creation of references, there should be some safe and built-in way of testing whether that's been done, so values don't get unexpectedly mangled. Test script: --------------- $a = 'test'; $b = "$a"; // Interpolated, so it should not be pooled or anything if PHP does that $c =& $a; // These all print if ($a == $b) print "\$a == \$b\n"; if ($b == $c) print "\$b == \$c\n"; if ($a == $c) print "\$a == \$c\n"; // These all print too, as expected if ($a === $b) print "\$a === \$b\n"; if ($b === $c) print "\$b === \$c\n"; if ($a === $c) print "\$a === \$c\n"; // I use "is" here, because other languages use it // if they don't already use /==+/ for this purpose. if ($a is $b) print "\$a is \$b\n"; // should not print if ($b is $c) print "\$b is \$c\n"; // should not print if ($a is $c) print "\$a is \$c\n"; // should run Expected result: ---------------- $a == $b $b == $c $a == $c $a === $b $b === $c $a === $c $a is $c Actual result: -------------- Parse error. (There is no "is" operator yet, and no reasonable replacement.) -- Edit bug report at http://bugs.php.net/bug.php?id=52907&edit=1 -- Try a snapshot (PHP 5.2): http://bugs.php.net/fix.php?id=52907&r=trysnapshot52 Try a snapshot (PHP 5.3): http://bugs.php.net/fix.php?id=52907&r=trysnapshot53 Try a snapshot (trunk): http://bugs.php.net/fix.php?id=52907&r=trysnapshottrunk Fixed in SVN: http://bugs.php.net/fix.php?id=52907&r=fixed Fixed in SVN and need be documented: http://bugs.php.net/fix.php?id=52907&r=needdocs Fixed in release: http://bugs.php.net/fix.php?id=52907&r=alreadyfixed Need backtrace: http://bugs.php.net/fix.php?id=52907&r=needtrace Need Reproduce Script: http://bugs.php.net/fix.php?id=52907&r=needscript Try newer version: http://bugs.php.net/fix.php?id=52907&r=oldversion Not developer issue: http://bugs.php.net/fix.php?id=52907&r=support Expected behavior: http://bugs.php.net/fix.php?id=52907&r=notwrong Not enough info: http://bugs.php.net/fix.php?id=52907&r=notenoughinfo Submitted twice: http://bugs.php.net/fix.php?id=52907&r=submittedtwice register_globals: http://bugs.php.net/fix.php?id=52907&r=globals PHP 4 support discontinued: http://bugs.php.net/fix.php?id=52907&r=php4 Daylight Savings: http://bugs.php.net/fix.php?id=52907&r=dst IIS Stability: http://bugs.php.net/fix.php?id=52907&r=isapi Install GNU Sed: http://bugs.php.net/fix.php?id=52907&r=gnused Floating point limitations: http://bugs.php.net/fix.php?id=52907&r=float No Zend Extensions: http://bugs.php.net/fix.php?id=52907&r=nozend MySQL Configuration Error: http://bugs.php.net/fix.php?id=52907&r=mysqlcfg