Register / Resolve T or IEnumerable<T>

Description

As initially discussed in issue #115 we have an issue where IEnumerable<T> may need to be resolved. This is a particular issue with Shiny integration where multiple delegates may be registered and will need to be resolved.

Problem

Prism registers services with an expectation that we will internally only want to resolve the last registration for any particular service. However it is possible for developers, or 3rd party plugins such as Shiny to require registering multiple services as is the case for Delegates. In this scenario it would be normal to see:

c.Register<ISomeDelegate, DelegateA>();
c.Register<ISomeDelegate, DelegateB>();

Expectations

What we need is a proper ruleset for the Container so that:

• When we Resolve<ISomeDelegate>() we should get DelegateB
• When we Resolve<IEnumerable<ISomeDelegate>>() we should get back a collection with both DelegateA and DelegateB.

NOTE: The registrations cannot directly reference the underlying container since this should transparently work with the Prism Container Abstractions and the integration where we convert from IServiceCollection to register each Service Descriptor with the Prism Container.

Observations

Currently we use the default IfAlreadyRegistered.Replace, this satisfies the first requirement, but fails on the second as we only get a collection with DelegateB.

If we do not set the IfAlreadyRegistered behavior or set it explicitly to Append, we succeed on the second requirement but fail on the first.

cc: @dadhi… any thoughts?

[dadhi]

@dahlbyk

DryIoc supports resolving a few different collection types (everything implemented by object[]

It is correct. Plus its own LazyEnumerable.

Is there a downside to checking if a wrapper is registered for the specified type?

No downside I am aware of. That way you will check for whatever wrapper suported by DryIoc.

[dansiegel]

fixed by #126