Dependency inversion of PHP factories with callables

factory-callable.php

<?php

// This example shows:
// 1) How to invert the dependency of initialization of factories in dependent
//    modules by giving a callable. This will defer the initialization of the
//    dependency.
// 2) How to use a closure inside of a class as a callable. Notice how accessing
//    "$this->presenter" gives the current presenter, not the one that was stored
//    when the closure was created.

// Submodule

interface Presenter {
	public function present();
}

class View {
	private $presenter;
	public function __construct( Presenter $presenter ) {
		$this->presenter = $presenter;
	}

	public function show() {
		printf("%s\n", $this->presenter->present());
	}
}

class ViewFactory{

	private $createPresenter;
	public function __construct( callable $createPresenter ) {
		$this->createPresenter = $createPresenter;
	}

	public function getView() {
		return new View( call_user_func( $this->createPresenter ) );
	}
}

// Main Module

class PresenterA implements Presenter {
	public function present() {
		return "Presenter A";
	}
}

class PresenterB implements Presenter {
	public function present() {
		return "Presenter B";
	}
}

class MainFactory {
	private $subFactory;
	private $presenter;
	public function __construct() {
		$this->presenter = new PresenterA();
		$this->viewFactory = new ViewFactory( function() {
			return $this->presenter;
		} );
	}

	public function setPresenter( Presenter $presenter ) {
		$this->presenter = $presenter;
	}

	public function getView() {
		return $this->viewFactory->getView();
	}
}

$factory = new MainFactory();
$factory->setPresenter(new PresenterB());

// Expected output: 'Presenter B'
$factory->getView()->show();




?>