PHP - Singleton Pattern

(example I looked at: http://develturk.com/tags/selfinstance/)

I've looked into the singleton pattern and a few examples. I've understood most of its concept, but I still have a few things puzzling me. I noticed that you're not supposed to allow cloning (obviously) or the construction method as it shows in an example:


    //this object can not copy
    //except the getInstance() method.
    private function __clone() {}
   
    //prevent directly access
    //we want acces this only from getInstance method.
    private function __construct(){}


Do I also have to do this for child classes, or just the parent class?

Hey guys.  So I'm trying to write a script that replaces footnote citations in one format with footnote citations in another format.

For example, the text will read:   "Then he went down the street.[1] That is where the police found him [2].  They immediately arrested him at the house. [3]"

And I would like the script to find the [ #] strings and replace them with {#} ... so that the string reads:
"Then he went down the street.{1} That is where the police found him {2}.  They immediately arrested him at the house. {3}"

Note that there will be double, and even tripple, digit footnotes, so the script has to be able to recognize [##] or [###] and replace the brackets with {} accordingly.

I'm not really sure how to do this, since the "pattern" is constantly changing depending on the number between the brackets.  Ideas?

Thanks!

Hi, i made a singleton class to make connecting to the db easyer. I got some questions. 1: is this the right way i wrote this class? 2: how can i easy implement mysqli prepare in this class? I've looked everywhere but prepared staments need more lines of code to make it work and i don't know how to implement that in the singleton class.

<?php
	require_once(dirname(dirname(__FILE__)) . "/config.php");
	
	class Database {
		public static $instance;
		private $mysqli,
				$query,
				$results,
			    $count = 0;
	 
		public static function getInstance() {
			if (!self::$instance) {
				self::$instance = new Database();
			}
			return self::$instance;
		}
			
		public function __construct() {
			$this->mysqli = new mysqli(DB_SERVER, DB_USERNAME, DB_PASSWORD, DB_DATABASE);
			if ($this->mysqli->connect_error) {
				die($this->mysqli->connect_error);
			}
		}

		public function query($sql) {
			if ($this->query = $this->mysqli->query($sql)) {
				while ($row = $this->query->fetch_assoc()) {
					$this->results[] = $row;
				}
				$this->count = $this->query->num_rows;
			}
			return $this;
		}
		
		public function results() {
			return $this->results;
		}

		public function count() {
			return $this->count;
		}
	 
	 
	}
?>

usage:

<?php
 include('database.php');
 $r = Database::getInstance()->query('SELECT * FROM users');
foreach ($r->results() as $row) {
   echo $row['name'] . '</br>';
}
echo $r->count();
?>

I have a singleton class that I am revamping and need a little help with. I want to use the following syntax for my queries without having to declare a global object. Below is my current code:

  Code: [Select]
   /**
     * The db database object
     *
     * @access private
     * @var object
     */
    private $db;
 
    /**
     * MySQLi database object
     *
     * @access private
     * @var object
     */
    private static $instance;
 
    /**
     * Current result set
     *
     * @access private
     * @var object
     */
    private $result;
 
    /**
     * The last result (processed)
     *
     * @access private
     * @var array
     */
    private $last_result;
 
    /**
     * The number of rows from last result
     *
     * @access private
     * @var int
     */
    private $row_count;
 
    /**
     * Last error
     *
     * @access private
     * @var string
     */
    private $last_error;
 
    /**
     * PHP5 Constructor
     *
     * Making this function 'private' blocks this class from being directly created.
     *
     * @access private
 
     */
    private function __construct() { }
 
    /**
     * Creates and references the db object.
     *
     * @access public
     * @return object MySQLi database object
     */
    public static function instance() {
        if ( !self::$instance )
            self::$instance = new db();
        return self::$instance;
    }
 
    /**
     * Connect to the MySQL database.
     *
     * @param string $host MySQL hostname
     * @param string $user MySQL username
     * @param string $password MySQL password
     * @param string $name MySQL database name
     * @return bool True if successful, false on error.
     */
    public function connection($host, $user, $password, $name) {
        // Connect to the database
        $this->db = new mysqli($host, $user, $password, $name);
        // Check connection
        if ( mysqli_connect_errno() ) {
            $this->last_error = mysqli_connect_error();
            return false;
        }
        return true;
    }

    public function query($sql) {
        $this->result = $this->db->query($sql);
        return $this->result;
    }
So then, what would I need to change in my class so that I will not have to declare a global variable for other classes and functions to use like db::query->();? Thanks in advance for your help.

OK, so I'm trying to create a central db class for data validation, etc.  I'm starting off with the data.

this code works for me, I just want to be sure that I'm not missing anything.  Will dbData be accessible globally?

Code: [Select]
class dbData{
    function regex_key_data($reg){
            $z = '/[a-z\s\'{1}]*/';
            $d=       array(  'domain'=>'/^[a-z0-9-.]+\.[a-z0-9]{2,4}$/i',
                        'email'=>'/^[a-z0-9._-]+@[a-z0-9._-]+\.[a-z]+$/i',
                        'GUID'=>'/[A-Z0-9]{8}-[A-Z0-9]{4}-[A-Z0-9]{4}-[A-Z0-9]{4}-[A-Z0-9]{12}/',
                        'html'=>'*htmlentities',
                        'int'=>'[0-9]',
                        'string'=>'*mysql_real_escape_string',
                        'fname'=>$z,
                        'lname'=>$z
                    );
            return $d[$reg];
    }
    function test($reg,$val){
       
        $z = preg_match(dbData::regex_key_data($reg),$val ,$dom);
        return ($z?$dom[0]:false);
    }
   
}
function clean_it($v,$type = 'none'){
    $v = urldecode($v);

    if(!empty($v)){

            switch($type){
                    case 'domain':
                           
                            return dbData::test('domain',$v);
                            break;
                    case 'email':
                            preg_match('/^[a-z0-9._-]+@[a-z0-9._-]+\.[a-z]+$/i', $v,$email);
                            if(empty($email[0])){return 'empty';}
                            else{return mysql_real_escape_string($email[0]);}
                            break;
                    case 'GUID':
                            return mysql_real_escape_string($v);
                            break;
                    case 'html':
                            return mysql_real_escape_string(htmlentities($v));
                            break;
                    case 'int':
                            if(is_numeric($v)){return $v;}
                            break;
                    case 'string':
                            return mysql_real_escape_string($v);
                            break;
            }

    }
    else{
        switch($type){
                case 'domain':
                case 'none':
                case 'string':
                case 'email':
                case 'GUID':
                case 'html':
                        return 'empty';
                        break;
                case 'int':
                        return 0;
                        break;
        }
    }
}
$br = '<br/>';
echo dbData::test('GUID','ASDFASDF-ASDF-ASDF-ASDF-ASDFASDFASDF').$br;
echo dbData::test('email','asdf@asdf.asd').$br;
echo clean_it('asdfsdf.com','domain');