Simple IoC Container

gistfile1.php

<?php

class Container
{
    protected $index = array();

    public function make($abstract)
    {
        if ($this->has($abstract)) {
            return $this->resolve($this->index[$abstract]);
        } else {
            return $this->resolve($abstract);
        }
    }

    protected function resolve($concret)
    {
        $reflector = new ReflectionClass($concret);
        $method = $reflector->getConstructor();

        // the class doesn't have a cosntructor
        if (is_null($method)) {
            return new $concret();
        }

        $dependencies = $method->getParameters();
        $parameters = array();

        foreach ($dependencies as $dependency) {
            $dependencyClass = $dependency->getClass();

            if (!$dependencyClass) {
                continue;
            } else {
                $dependencyClass = $dependencyClass->name;
            }

            if ($this->has($dependencyClass)) {
                $dependencyObject = $this->make($dependencyClass);
            } else {
                $dependencyObject = $this->resolve($dependencyClass);
            }

            array_push($parameters, $dependencyObject);
        }

        return $reflector->newInstanceArgs($parameters);
    }

    public function has($key)
    {
        return array_key_exists($key, $this->index);
    }

    public function bind($abstract, $concret)
    {
        if (!is_string($abstract) && !is_callable($concret)) {
            throw new InvalidArgumentException("binding name must be a string or callable object.");
        }

        if ($this->has($abstract)) {
            throw new InvalidArgumentException($abstract." is already binded.");
        }

        $this->index[$abstract] = $concret;
    }
}

interface Flyable
{
    public function fly();
}

class HummingBird implements Flyable
{
    public function fly()
    {
        echo "I'm flying~~~";
    }
}

$container = new Container();
$container->bind('Flyable', 'HummingBird');

$bird = $container->make('Flyable');

var_dump($bird);