PSR-11 Support / Custom factories

We're using third party libraries more and more because Magento is pretty much completely compatible with third party libraries. Unfortunately I see more libraries using PSR-11 and that is causing headaches when trying to use those libraries.

For example, I'm using this library: https://github.com/prooph/event-sourcing
This library makes use of the ContainerInterface to instantiate its objects.. it would be nice if Magento would support custom factories for objects.

Not sure how that would exactly work, how the config would be used in the config, etc.

Config examples:

• Zend https://github.com/prooph/proophessor-do/blob/master/config/autoload/prooph.global.php
• Symfony https://github.com/prooph/proophessor-do-symfony/blob/master/config/services.yaml

Maybe define something like:

<type name="ReachDigital\ProophJira\Infrastructure\Repository\EventStoreUserCollection">
    <factory type="Prooph\EventSourcing\Container\Aggregate\AggregateRepositoryFactory"/>
</type>

This probably needs to be thought out more ;)

Start by reviewing the PSR-11 use case and the linked Zend prooph.global.php and Symfony services.yaml configuration examples. Define how Magento configuration would support custom factories and what the expected behavior and acceptance tests should be before implementation.