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

[Chris Lattner]

On Dec 3, 2017, at 3:47 PM, Jonathan Hull <jhull at gbis.com> wrote:
>> That’s a good principle.  However, a dynamic member lookup is just a member lookup.  By that principle, it should look like a member lookup :-)
> 
> The behavior is different though (the invisible guard rails which we normally rely on to prevent mistakes are missing), so it should look similar without being identical.

Member lookup is already entirely API author defined.  You can define computed properties that do anything on get and set.  There is nothing fundamentally new here at all.

-Chris