[swift-evolution] Proposal: Introduce User-defined "Dynamic Member Lookup" Types

Thorsten Seitz tseitz42 at icloud.com
Sun Dec 3 16:11:43 CST 2017

> Am 03.12.2017 um 20:08 schrieb Magnus Ahltorp <map at kth.se>:
>> 4 Dec. 2017 03:54 Thorsten Seitz via swift-evolution <swift-evolution at swift.org> wrote:
>> The difference is that IUOs are marked by a "!“ whereas dynamic member lookups look just like normal member lookups but unlike them can fail.
> IUOs are not marked with an "!" by the caller, that's what makes them implicit. They *are* marked at the declaration, but so would dynamic member lookups be.

You are right, my mistake. 


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