[foreign] "implicit" conversions in the memory access API

[Maurizio Cimadamore]

On 25/03/2021 21:12, Maurizio Cimadamore wrote:
> Yep, I think so too - this will then become the moral successor of the 
> old NativeScope. 

Too fast - I was suddently reminded of another issue with subtyping, 
which I didn't list in my original email.

In the current incarnation of the API, you use a scope to build an 
allocator.

ResourceScope scope = ...
SegmentAllocator allocator = SegmentAllocator.arenaUnbounded(scope);

This is relatively clean, in the sense that you can combine different 
allocation schemes with different types of scopes.

I believe this composition is a direct result of the fact that 
ResourceScope and SegmentAllocator are unrelated types. Once you start 
treating ResourceScope as a SegmentAllocator, I think it gets messier.

So, back to the previous list

> * we do nothing and leave the API as is (1=D, 2=B)
> * we go back, remove the Addressable interface (1=A, 2=B)
> * as before, but we also remove the ResourceScope overloads - no magic 
> conversions, everything is always explcit (1=A, 2=A)
> * we see if there's an interface name we like for ResourceScope -> 
> SegmentAllocator, and remove the overloads, which would then be no 
> longer necessary (1=D, 2=D)
> * make ResourceScope <: SegmentAllocator, but leave Addresable (1=D, 2=C) 
I think it's either the first bullet (leave everything as is), or the 
4th bullet (find a common supertype).

Maurizio