SharedObjectFactory.php

<?php

class SharedObjectFactory {

    private $container;
    private $config;

    public function __construct( array $config ) {
        $this->container = [];
        $this->config = $config;
    }

    private function getSharedObject( string $id, callable $factory ) {
        if( !isset( $this->container[$id] ) ) {
            $this->container[$id] = $factory();
        }
        return $this->container[$id];
    }

    private function getGreeter(): GreetService {
        return $this->getSharedObject(
            GreetService::class,
            function() {
                return new FixedMessageGreeter( $this->config['greeting'] );
            }
        );
    }

    public function getPresenter(): Presenter {
        return $this->getSharedObject(
            GreetingPresenter::class,
            function() {
                return new GreetingPresenter(
                    $this->getGreeter(),
                    $this->newLogger()
                );
            }
        );
    }

    /**
     * Example of a non-shared service
     */
    public function newLogger(): Logger {
        return new SuchLogger();
    }

}

Example: https://github.com/wmde/wikimedia.de/blob/master/src/TopLevelFactory.php