[swift-evolution] Question about heterogeneous collections

[Jason Sadler]

Hi folks,

I have an issue with using a heterogeneous array of objects conforming to a
protocol - I want to write an extension on Array (or CollectionType) that
applies only when Element : MyProtocol, but I can’t call methods in that
extension from an instance of [MyProtocol] because "Using ‘MyProtocol' as a
concrete type conforming to protocol ‘MyProtocol' is not supported”

(For more background, my full use case can be seen in this gist:
https://gist.github.com/sadlerjw/2cc16b4375b02fe7f400)

I’ve asked about this on swift-users (
https://lists.swift.org/pipermail/swift-users/Week-of-Mon-20160321/001560.html)
and got some good workarounds but no one was able to provide me with
information on any future plans in swift to address this issue - whether
that’s making protocols conform to themselves, or some other improved
approach to heterogeneous collections. I wonder if anyone here can shed
some light on this? (I’m new to the mailing lists, sorry!)

Thanks
Jason
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