PHPのエラー処理とログ記録

<?php
    // 我们将要定义自己的错误处理
    error_reporting(0);
    // 用户自定义错误处理函数
    function userErrorHandler($errno, $errmsg, $filename, $linenum, $vars)
    {
        // 错误发生的时间
        $dt = date("Y-m-d H:i:s (T)");
        // 定义错误字符串的关联数组
        // 在这里我们只考虑
        // E_WARNING, E_NOTICE, E_USER_ERROR,
        // E_USER_WARNING 和 E_USER_NOTICE
        $errortype = array (
            E_ERROR => &#39;Error&#39;,
            E_WARNING => &#39;Warning&#39;,
            E_PARSE => &#39;Parsing Error&#39;,
            E_NOTICE => &#39;Notice&#39;,
            E_CORE_ERROR => &#39;Core Error&#39;,
            E_CORE_WARNING => &#39;Core Warning&#39;,
            E_COMPILE_ERROR => &#39;Compile Error&#39;,
            E_COMPILE_WARNING => &#39;Compile Warning&#39;,
            E_USER_ERROR => &#39;User Error&#39;,
            E_USER_WARNING => &#39;User Warning&#39;,
            E_USER_NOTICE => &#39;User Notice&#39;,
            E_STRICT => &#39;Runtime Notice&#39;,
            E_RECOVERABLE_ERROR => &#39;Catchable Fatal Error&#39;
        );
        // 设置要保存变量跟踪信息的错误类别
        $user_errors = array(E_USER_ERROR, E_USER_WARNING, E_USER_NOTICE);
        $err = "<errorentry>\n";
        $err .= "\t<datetime>" . $dt . "</datetime>\n";
        $err .= "\t<errornum>" . $errno . "</errornum>\n";
        $err .= "\t<errortype>" . $errortype[$errno] . "</errortype>\n";
        $err .= "\t<errormsg>" . $errmsg . "</errormsg>\n";
        $err .= "\t<scriptname>" . $filename . "</scriptname>\n";
        $err .= "\t<scriptlinenum>" . $linenum . "</scriptlinenum>\n";
        if (in_array($errno, $user_errors)) {
            $err .= "\t<vartrace>" . wddx_serialize_value($vars, "Variables") . "</vartrace>\n";
        }
        $err .= "</errorentry>\n\n";
        // for testing
        // echo $err;
        // 记录错误信息到错误日志，并在发生关键用户错误时发送电子邮件
        error_log($err, 3, "/usr/local/php4/error.log");
        if ($errno == E_USER_ERROR) {
            mail("phpdev@example.com", "Critical User Error", $err);
        }
    }
    function distance($vect1, $vect2)
    {
        if (!is_array($vect1) || !is_array($vect2)) {
            trigger_error("Incorrect parameters, arrays expected", E_USER_ERROR);
            return NULL;
        }
        if (count($vect1) != count($vect2)) {
            trigger_error("Vectors need to be of the same size", E_USER_ERROR);
            return NULL;
        }
        for ($i=0; $i<count($vect1); $i++) {
            $c1 = $vect1[$i]; $c2 = $vect2[$i];
            $d = 0.0;
            if (!is_numeric($c1)) {
                trigger_error("Coordinate $i in vector 1 is not a number, 
                    using zero",E_USER_WARNING);
                $c1 = 0.0;
            }
            if (!is_numeric($c2)) {
                trigger_error("Coordinate $i in vector 2 is not a number, 
                    using zero",E_USER_WARNING);
                $c2 = 0.0;
            }
            $d += $c2*$c2 - $c1*$c1;
        }
        return sqrt($d);
    }
    $old_error_handler = set_error_handler("userErrorHandler");
    // 未定义的常量，将产生一个警告
    $t = I_AM_NOT_DEFINED;
    // 定义一些 "载体"
    $a = array(2, 3, "foo");
    $b = array(5.5, 4.3, -1.6);
    $c = array(1, -3);
    // 引发一个用户错误
    $t1 = distance($c, $b) . "\n";
    // 再次引发一个用户错误
    $t2 = distance($b, "i am not an array") . "\n";
    // 引发一个警告
    $t3 = distance($a, $b) . "\n";
?>