shared instances

saredInstances.php

<?php
/**
 * Class SomeClass
 *
 * @package TimJensen
 */
class SomeClass {
	protected $one;
	protected $two;
	protected $three;

	public function __construct( $one, $two ) {
		$this->one = $one;
		$this->two = $two;
	}

	public function setThree( $three ) {
		$this->three = $three;
	}
}

/**
 * Class ClassFactory
 *
 * @package TimJensen
 */
class ClassFactory {

	/**
	 * Holds the shared class instances.
	 *
	 * @var array
	 */
	protected static $instances = [];

	/**
	 * Makes a new instance of the class if one has not already been set.
	 *
	 * @param string $class_name Fully qualified name of the class to instantiate.
	 * @param array  $args       Arguments passed to the class constructor.
	 * @return mixed|null
	 */
	public static function make( string $class_name, $args = [] ) {
		if ( ! isset( self::$instances[ $class_name ] ) ) {
			try {
				$reflection_class = new \ReflectionClass( $class_name );
				$class_instance   = $reflection_class->newInstanceArgs( $args );

				self::$instances[ $class_name ] = $class_instance;
			} catch ( \Exception $e ) {
				trigger_error( $e->getMessage(), E_USER_ERROR );
			} catch ( \ArgumentCountError $e ) {
				trigger_error( $e->getMessage(), E_USER_ERROR );
			}
		}

		return self::$instances[ $class_name ] ?? null;
	}

	/**
	 * Returns the shared instance of the specified class.
	 *
	 * @param string $class_name Fully qualified name of the class instance to retrieve.
	 * @return mixed|null
	 */
	public static function get( string $class_name ) {
		return self::$instances[ $class_name ] ?? null;
	}
}

var_dump( ClassFactory::make( SomeClass::class, [ 'one', 'two' ] ) );

/** @var SomeClass $some_class */
$some_class = ClassFactory::get( SomeClass::class );
$some_class->setThree( 'three' );

var_dump( ClassFactory::get( SomeClass::class ) );