Interface "indexing"

[Kagamin via Digitalmars-d-learn]

On Sunday, 6 September 2015 at 17:32:11 UTC, Prudence wrote:
> And to fire the event, instead of a huge switch(or essentially 
> the same), one can write one line of code or so and have D take 
> care of matching up things. (essentially for some enum value I 
> want a corresponding type to be associated with it)

If you want it happen at runtime, how it can be not a switch?