[swift-users] Can't implement generic subscript in protocol

Joanna Carter joanna at carterconsulting.org.uk
Fri Sep 15 04:03:01 CDT 2017


Now we've got generic subscripts, I thought I'd play…

protocol DataProvider
  subscript<itemType>(index: Int) -> itemType { get }

class Test : DataProvider // error : Type 'Test' does not conform to protocol 'DataProvider'
  subscript(index: Int) -> String
    return "Fred"

Simple questions:

1. why does this not compile?
2. should it?
3. is there a workaround without declaring an associated type in the protocol?


Joanna Carter
Carter Consulting

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