Log Class

Log Class

This class provides simple logging functionality but logging error messages to a log file. The name of the log file can be set if multiple log files need to be written for different scripts. This form of logging is a great debugging tool for those using ajax in their scripts as errors are often hidden.

However, it is not just for error tracking, and can be used to record any type of events such as logins, forum posts, email sending or any place where a record needs to be maintained.

The class makes use of the singleton design pattern so that the same instance of the logger class is always returned, and to provide a globally accessable method of logging.


<?php
/**
 *
 * @Class logger
 *
 * @Purpose: Logs text to a file
 *
 * @Author: Kevin Waterson
 *
 * @copyright PHPRO.ORG (2009)
 *
 * @example usage
 * $log = logger::getInstance();
 * $log->logfile = '/tmp/errors.log';
 * $log->write('An error has occured', __FILE__, __LINE__);
 *
 */class logger{
    /*** Declare instance ***/
    private static $instance = NULL;

    /**
     *
     * @Constructor is set to private to stop instantion
     *
     */
    private function __construct()
    {
    }

    /**
     *
     * @settor
     *
     * @access public
     *
     * @param string $name
     *
     * @param mixed $value
     *
     */
    public function __set($name, $value)
    {
        switch($name)
        {
            case 'logfile':
            if(!file_exists($value) || !is_writeable($value))
            {
                throw new Exception("$value is not a valid file path");
            }
            $this->logfile = $value;
            break;

            default:
            throw new Exception("$name cannot be set");
        }
    }

    /**
     *
     * @write to the logfile
     *
     * @access public
     *
     * @param string $message
     *
     * @param string $file The filename that caused the error
     *
     * @param int $line The line that the error occurred on
     *
     * @return number of bytes written, false other wise
     *
     */
    public function write($message, $file=null, $line=null)
    {
        $message = time() .' - '.$message;
        $message .= is_null($file) ? '' : " in $file";
        $message .= is_null($line) ? '' : " on line $line";
        $message .= "\n";
        return file_put_contents( $this->logfile, $message, FILE_APPEND );
    }

    /**
    *
    * Return logger instance or create new instance
    *
    * @return object (PDO)
    *
    * @access public
    *
    */
    public static function getInstance()
    {
        if (!self::$instance)
        {
            self::$instance = new logger;
        }
        return self::$instance;
    }


    /**
     * Clone is set to private to stop cloning
     *
     */
    private function __clone()
    {
    }

} /*** end of log class ***/
?>

EXAMPLE USAGE


<?php
try
{
    /*** a new logger instance ***/
    $log = logger::getInstance();
    /*** the file to write to ***/
    $log->logfile = '/tmp/errors.log';
    /*** write an error message with filename and line number ***/
    $log->write('An error has occured', __FILE__, __LINE__);
}
catch(Exception $e)
{
    echo $e->getMessage();
}?>