Singleton Design Pattern in PHP

Singleton Design Pattern is a creational design pattern for Object Oriented Programming.
Singleton Pattern ensures that only one object of that class exists and provides a single point of access to it for any other code.

In these scenerios, we need a Singleton class instance -

1. If we don't want to recreat any object second time, then we need to use a way like Singleton.
2. If there is a possibility of Memory optimization and one specific class must call one time, then we use singleton pattern.

Creating a Singleton instance is very simple -

<?php

class SingletonPatternExample
{
    /**
     * Singleton Instance
     *
     * @var SingletonPatternExample
     */
    private static $instance;

    /**
     * Private Constructor
     *
     * We can't use the constructor to create an instance of the class
     *
     * @return void
     */
    private function __construct()
    {
        // Don't do anything, we don't want to be initialized
    }

    /**
     * Get the singleton instance
     *
     * @return SingletonPatternExample
     */
    public static function getInstance()
    {
        if (!isset(self::$instance)) {
            self::$instance = new self();
        }

        return self::$instance;
    }
}

So, we can use this like -

<?php

// We have to call getInstance() static method
$singletonPattern = SingletonPatternExample::getInstance();

// Call our doSomething() method.
$singletonPattern->doSomething();

We can't call Singleton like this -

$singletonPattern = new SingletonPatternExample();

It will throw an exception.

Get More example with Extendable Singleton Pattern with trait and re-usable pattern for PHP -

https://devsenv.com/tutorials/how-to-make-a-singleton-design-pattern-in-php