In PHP, what is the concept of singleton design pattern?

Singleton pattern ensures that a class has only one instance and provides a global access point. It ensures that only one object is available and under control in the application. The Singleton pattern provides a way to access its unique object directly without instantiating the object of the class.

Example

<?php
   class database {
      public static $connection;
      private function __construct(){
         echo "connection created";
      }
      public function connect(){
         if(!isset(self::$connection)){
            self::$connection = new database();
         }
         return self::$connection;
      }
   }
   $db = database::connect();
   $db2 = database::connect();
?>

Output

connection created

Explanation

In the above example, we follow the singleton pattern, so the object $db2 cannot be created. Only one object is created and is available throughout the application.

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