zf2样式对象工厂/闭包

Question

I am using the Command pattern, and trying to copy zf2-style service configurations by using closures in an attempt to load the command objects dependencies within the closure. For example, in my command factory:

protected function getCommandConfig(){
    return [
        'view-details-command' => function () { 
            $userFactory = new My\Model\User\Factory();

            $editUserForm = new My\Form\User\Edit();
            $editUserForm ->setInputFilter(new My\InputFilter\EditUser());

            $command = new My\Command\ViewUserDetailsCommand($userFactory, $editUserForm);
            return $command;
        }
    ];
}

... which is pretty much identical to how ZF2 initialises objects in the service manager. However, when i run this, such as as $command = $this->getCommandConfig()[$commandName] i get a closure object returned, with an exception raised when i call a method on what i am expecting to be a command object ("Call to undefined method Closure::foobar...."). What should i be doing to use this sort of configuration? (I am not using the entire ZF2 stack).