Some confusion regarding object creation in static function

[akhileshbc]

Hi guys

I have been going through some piece of code and got confused at a certain point. The below is a piece of code:

class DataManager
{
  private static function _connect()
  {
    return new PDO('mysql:host=localhost;dbname=sample', 'root','');
  }

  public static function fetch_users()
  {
    $db = self::_connect();

    $st = $db->query("SELECT * FROM users");
    //....
  }
  
  public static function func2()
  {
    $db = self::_connect();

    $st = $db->query("SELECT * FROM users");
    //....
  }

  public static function func2()
  {
    $db = self::_connect();

    $st = $db->query("SELECT * FROM users");
    //....
  }
  
  //and so on..
} 

Isn't that a bad practice ? I mean, each time when a member function is executed, the connect() function is called which will return a NEW PDO object. So, new PDO objects are created each time.

Am I correct ?

Thanks

[SambaNeko]

Yes, this is bad practice. _connect() should instead check if a connection object already exists, and return it if so, otherwise create a new one only as needed.

[penagate]

Yes, this is bad practice. _connect() should instead check if a connection object already exists, and return it if so, otherwise create a new one only as needed.

This is a common pattern.
I prefer just to create it anyway:

class DataManager
{
    public static function connect()
    {
        return new PDO('mysql:host=localhost;dbname=sample', 'root','');
    }

    public static function fetch_users()
    {
        $st = $db->query("SELECT * FROM users");
        //....
    }

    //...
}

DataManager::connect(); 

Also, I prefer using prepared statements wherever possible:

    public static function fetch_users()
    {
        static $stmt;
        if ($stmt === null)
            $stmt = $db->prepare('SELECT * FROM users');

        $st = $stmt->execute();

        //....
    } 

This is overkill for a simple query such as that one, but once you add parameters the benefits quickly outweight the cost.

Notice that the static keyword has a different meaning within a function: it creates a variable which is local to the function, but which retains its value between calls. Since this function is a class member, it is equivalent to creating a static class variable, but with an additional scope restriction.

[akhileshbc]

Thanks for the clarification

I got this piece of code from here: http://www.phpvault.net/
He had posted some video tutorials on youtube and the sourcecodes were uploaded in that site.