Who can explain the encapsulation class for error reporting implemented in PHP?

<?php
class MyErrorHandler {
  public $message;
  public $filename;
  public $line;
  public $vars = array();
  protected $_noticeLog = &#39;F:\root\noticeLog.log&#39;;
  public function __construct ($message,$filename,$line,$vars) {
    $this->message = $message;
    $this->filename = $filename;
    $this->line = $line;
    $this->vars = $vars;
  }
  public static function deal ($errno,$errmsg,$filename,$line,$vars) {
    $self = new self($errno,$errmsg,$filename,$line,$vars);
    switch ($errno) {
      case E_USER_ERROR:
        return $self->dealError();
        break;
      case E_USER_WARNING:
      case E_WARNING:
        return $self->dealWarning();
        break;
      case E_NOTICE:
      case E_USER_NOTICE:
        return $self->dealNotice();
      default:
        return false;
    }
  }
  /**
  * 致命的错误
  */
  public function dealError() {
    ob_start();
    debug_print_backtrace();
    $backtrace = ob_get_flush();
    $errorMsg = <<<EOF
出现了致命的错误，如下：
产生错误的文件：{$this->filename}
产生错误的信息：{$this->message}
产生错误的行号：{$this->line}
追踪信息{$backtrace}
EOF;
    error_log($errorMsg,1,&#39;279921301@qq.com&#39;,&#39;From:php[error错误日志]&#39;);
    exit(1);
  }
  /**
  * 警告的错误
  */
  public function dealWarning() {
    $errorMsg = <<<EOF
出现了警告的错误，如下：
产生警告的文件：{$this->filename}
产生警告的信息：{$this->message}
产生警告的行号：{$this->line}
EOF;
    return error_log($errorMsg,1,&#39;279921301@qq.com&#39;,&#39;From:php[error警告日志]&#39;);
  }
  /**
  * 通知的错误
  */
  public function dealNotice() {
    $datetime = date(&#39;Y-m-d H:i:s&#39;);
    $errorMsg = <<<EOF
出现了通知的错误，如下：
产生通知的文件：{$this->filename}
产生通知的信息：{$this->message}
产生通知的行号：{$this->line}
产生通知的时间：{$datetime}
EOF;
    return error_log($errorMsg,3,$this->_noticeLog);
  }
}

<?php
include "MyErrorHandler.php";
//报告所有 PHP 错误
error_reporting(-1);
//不显示错误信息
ini_set(&#39;display_errors&#39;,0);
set_error_handler(array(&#39;MyErrorHandler&#39;,&#39;deal&#39;));
echo $test; //Notice错误
settype($var,&#39;test&#39;); //警告错误
test();