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[2012-04-16 17:57 UTC] chealer at gmail dot com
Description: ------------ The at sign operator allows to "ignore" error messages, as explained in http://ca3.php.net/manual/en/language.operators.errorcontrol.php When prepended to an expression in PHP, any error messages that might be generated by that expression will be ignored. However, as reported in #61091, user-defined error handlers registered with set_error_handler() are nevertheless run when @ is used, which often causes such messages to show, as in the below example, where a custom error handler is used to customize the display of error messages. As http://ca3.php.net/manual/en/language.operators.errorcontrol.php#98895 and http://ca3.php.net/manual/en/language.operators.errorcontrol.php#85042 show, this problem is not new. This behavior appears to be by design, and might be wanted in some cases. Therefore, please either: Stop calling user-defined error handlers when suppressing errors. This needs serious consideration for backwards-compatibility. Allow specifying whether user-defined error handlers should be called when suppressing errors. Make the documentation reflect the current state of things. Alternatively, if the documentation of the @ operator isn't amended because custom error handlers are considered a corner case, then the set_error_handler() documentation should warn developers tempted to use custom error handlers that they are non-standard, not recommended/supported, and try to explain the pitfalls. In short, tell developers they should only use a custom error handler if they know what they're doing. However, this alternative should be avoided since set_error_handler() is already used in several applications whose developers didn't receive the warning. Test script: --------------- <?php function myErrorHandler($errno, $errstr) { switch ($errno) { case E_USER_ERROR: echo "<b>My ERROR</b> [$errno] $errstr<br />\n"; echo " Fatal error on line $errline in file $errfile"; echo ", PHP " . PHP_VERSION . " (" . PHP_OS . ")<br />\n"; echo "Aborting...<br />\n"; exit(1); break; case E_USER_WARNING: echo "<b>My WARNING</b> [$errno] $errstr<br />\n"; break; case E_USER_NOTICE: echo "<b>My NOTICE</b> [$errno] $errstr<br />\n"; break; default: echo "Unknown error type: [$errno] $errstr<br />\n"; break; } } // function to test the error handling function scale_by_log($vect, $scale) { if (!is_numeric($scale) || $scale <= 0) { trigger_error("log(x) for x <= 0 is undefined, you used: scale = $scale", E_USER_ERROR); } if (!is_array($vect)) { trigger_error("Incorrect input vector, array of values expected", E_USER_WARNING); return null; } $temp = array(); foreach($vect as $pos => $value) { if (!is_numeric($value)) { trigger_error("Value at position $pos is not a number, using 0 (zero)", E_USER_NOTICE); $value = 0; } $temp[$pos] = log($scale) * $value; } return $temp; } $a = array(2, 3, "foo", 5.5, 43.3, 21.11); /* Value at position $pos is not a number, using 0 (zero) */ scale_by_log($a, M_PI); @scale_by_log($a, M_PI); set_error_handler("myErrorHandler"); @scale_by_log($a, M_PI); ?> Expected result: ---------------- Notice: Value at position 2 is not a number, using 0 (zero) in /var/www/atoperator.php on line 42 Call Stack: 0.0005 339192 1. {main}() /var/www/atoperator.php:0 0.0005 339836 2. scale_by_log(array (0 => 2, 1 => 3, 2 => 'foo', 3 => 5.5, 4 => 43.3, 5 => 21.11), 3.1415926535898) /var/www/atoperator.php:55 0.0006 340648 3. trigger_error('Value at position 2 is not a number, using 0 (zero)', 1024) /var/www/atoperator.php:42 Actual result: -------------- Notice: Value at position 2 is not a number, using 0 (zero) in /var/www/atoperator.php on line 42 Call Stack: 0.0005 339192 1. {main}() /var/www/atoperator.php:0 0.0005 339836 2. scale_by_log(array (0 => 2, 1 => 3, 2 => 'foo', 3 => 5.5, 4 => 43.3, 5 => 21.11), 3.1415926535898) /var/www/atoperator.php:55 0.0006 340648 3. trigger_error('Value at position 2 is not a number, using 0 (zero)', 1024) /var/www/atoperator.php:42 <b>My NOTICE</b> [1024] Value at position 2 is not a number, using 0 (zero)<br /> PatchesPull RequestsHistoryAllCommentsChangesGit/SVN commits
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I meant it would be inefficient to ask PHP programmers to include if (!(error_reporting() & $errno)) { // This error code is not included in error_reporting return; } in all custom error handlers they write, if the problem could be addressed once and for all by the PHP interpreter. If that is your stance though, this requirement should be documented in http://ca3.php.net/manual/en/function.set-error-handler.php And if you really think that custom error handlers should ignore suppressed errors, then not calling custom error handlers would be more of a bugfix (for those handlers that fail to do it) than a BC break. Certainly, that wouldn't be a "major BC break", although it may be disruptive enough to warrant waiting for a major release to do such a behavior change. I'm not saying there's something *wrong* (in the sense of buggy) with the current implementation, as long as how it works is documented (which wasn't the case until recently), and the requirement to check for suppressed errors is documented in set_error_handler()'s documentation (which is still not the case).