IEnumerable Transitioning

[smudge202]

This behaviour needs further discussion @mattridgway / @AdamWilks et al.

In essence, several DI containers provide functionality allowing consumers to have an IEnumerable be injected. The expected behaviour is for the container to find all registered implementations assignable from IService.

I believe @mattridgway would like to introduce an observable variant which would allow consumers to subscribe for notifications of new services (assignable from IService) being registered.

Personally, I would like to see an extension that the Host projects can use to mark a service as Transitional (possibly separate from existing extensions), which would allow our IEnumerable implementation to append new services so that the next enumeration would yield both original and new services.

[smudge202]

/CC @herecydev

[herecydev]

I'm in favour of how tommys would work. That would be my expected behaviour of registering new services. I.e. add not replace.

[smudge202]

Regarding my personal preference on implementation, a potential downside would be if the consumer calls "ToList", the behaviour I described would obviously be no longer available.

Perhaps there is merit in defining a custom INamedEnumerable? That way we could add an overriding "ToList" extension that continues the described behaviour and does not allow Add/Update operations? (Sounds horrid, but bad idea > no idea).

[herecydev]

I think if someone was doing this they should be informed enough to know they are caching the results and ignoring any potential amendments. I actually dont see this as a huge negative. Just something to bear in mind

[smudge202]

@herecydev "It's not a bug, it's a feature"?