Helping with __mutable (which will be renamed to __metadata)

[Suleyman]

On Saturday, 13 April 2019 at 01:17:55 UTC, rikki cattermole 
wrote:
> I'm concerned that it will be used as an escape from the type 
> system arbitrarily. Right now there is nothing to discourage 
> the abuse of this storage class.
>
> Is there something we can do to discourage abuse?

 From skimping through the DIP it doesn't look too dangerous it 
seems like just a fancy 'shared' escape for immutable fields, the 
rest looks the same as casting immutable away in @system code.