src/Container.php
public function register(callable $inject) : void
    {
        $reflection = new ReflectionFunction($inject);
        $parameters = $reflection->getParameters();
        foreach ($parameters as $parameter) {
            $key = $parameter->name;
            $getter = function ($c) use ($reflection, $parameters, $key) {
                if (isset($c->delegate)) {
                    try {
                        return $c->delegate->get($key);
                    } catch (NotFoundExceptionInterface $e) {
                        // That's fine, we'll try our own container next.
                    }
                }
                $args = [];
                foreach ($parameters as $param) {
                    if (!$param->isPassedByReference()) {
                        $args[] = $c->get($param->name);
                    } else {
                        ${$param->name} = null;
                        $args[$param->name] =& ${$param->name};
                    }
                }
                $reflection->invokeArgs($args);
                foreach ($args as $found => $value) {
                    if (!is_numeric($found) && $found == $key) {
                        $c::$map[$found] = $value;
                    }
                }
                if (array_key_exists($key, $args)) {
                    return $args[$key];
                }
                throw new NotFoundException($key);
            };
            static::$map[$key] = new ReflectionFunction($getter);
        }
    }
public function register(callable $inject) : void
    {
        $reflection = new ReflectionFunction($inject);
        $parameters = $reflection->getParameters();
        foreach ($parameters as $parameter) {
            $key = $parameter->name;
            $getter = function ($c) use ($reflection, $parameters, $key) {
                if (isset($c->delegate)) {
                    try {
                        return $c->delegate->get($key);
                    } catch (NotFoundExceptionInterface $e) {
                        // That's fine, we'll try our own container next.
                    }
                }
                $args = [];
                foreach ($parameters as $param) {
                    if (!$param->isPassedByReference()) {
                        $args[] = $c->get($param->name);
                    } else {
                        ${$param->name} = null;
                        $args[$param->name] =& ${$param->name};
                    }
                }
                $reflection->invokeArgs($args);
                foreach ($args as $found => $value) {
                    if (!is_numeric($found) && $found == $key) {
                        $c::$map[$found] = $value;
                    }
                }
                if (array_key_exists($key, $args)) {
                    return $args[$key];
                }
                throw new NotFoundException($key);
            };
            static::$map[$key] = new ReflectionFunction($getter);
        }
    }
Register a group of dependencies defined in the callable. Each referenced
argument should be assigned its designated value when invoked. Note that
invocation takes place only when a dependency is retrieved.

@param callable $inject A callable associating values with keys.
@return void