Are D classes proper reference types?

[kinke]

On Saturday, 26 June 2021 at 07:00:37 UTC, Ola Fosheim Grøstad 
wrote:
>> Weak pointers aren't in the language, so I don't see why they 
>> would matter here. I thought you were after replacing 
>> GC-allocated class instances by a simple RC scheme.
>
> One goal could be to make a class compatible with C++ or Swift 
> on request. Both support weak pointers. You could have multiple 
> ref-count layout schemes as long as they all are on negative 
> offsets. Just don't mix class hierarchies. So you could mix a  
> D class hierarchy, C++ class-hiearchy and Swift class-hierarchy 
> in the same codebase?

I'm pretty sure I haven't seen a weak pointer in C++ yet. I don't 
look at C++ much anymore, but I suspect they are even a lot rarer 
than shared_ptr. Wrt. mixed class hierarchies, being able to 
inherit from and instantiate C++ classes in D is of some priority 
and mostly works today. (Let's not get into discussing multiple 
inheritance here, it's hardly a show-stopper for most use cases.)

Is Swift a thing outside the Apple universe (I admittedly despise 
;))? It's surely much better than their Objective-C crap, but 
still...

So for rare use cases like shared_ptr/weak pointer interop, a 
library solution (just like they are in C++) is IMO enough.