Dependency Injection Example

dependency-injection.php

<?php

class App
{
    /**
     * Application Registry
     *
     * @var array
     */
    protected $registry = [];

    /**
     * Magic method to set the property
     * @param string $name
     * @param callback $resolver
     */
    public function __set($name, $resolver)
    {
        $this->registry[$name] = $resolver;
    }

    /**
     * Magic method to return the registry property
     *
     * @param  string $name
     * @return callback
     */
    public function __get($name)
    {
        return $this->registry[$name]();
    }
}

class Invoice
{
    /**
     * Sample method
     *
     * @return string
     */
    public function doSomething()
    {
        return 'we did something';
    }
}

$app = new App;
$app->invoice = function() {
    $inv = new Invoice;
    return $inv;
};

var_dump($app->invoice->doSomething());