Virtual packages and "provide" Composer feature

[tassoevan]

What about require in composer.json something like slim/slim-views-implementation and make specific packages for each template system (including Plates, as suggested in a PR) matching this requirement viaprovidefeature of Composer? Exactly likepsr/log-implementation` works.

[silentworks]

@tassoevan this is something I am considering doing as I don't really like the suggest node of composer.json, I will run it by @codeguy and see what his thoughts are.