openImplicit

[Michael Hall]

> On Apr 21, 2023, at 7:24 PM, Maurizio Cimadamore <maurizio.cimadamore at oracle.com> wrote:
> 
> 
> On 21/04/2023 22:16, Michael Hall wrote:
>> I may of misunderstood implicit. I thought that gave you a garbage collection managed memory segment. So heap? I guess I was wrong.
> 
> With implicit/auto you can create a _native_ memory segment whose lifetime is managed automatically by the garbage collector. So, in a way, you're right that it works like a Java array, in the sense that when the segment becomes unreachable, its backing off-heap memory can be reclaimed (at some unspecified point). This is also the way in which the backing native memory of a direct byte buffer is managed.
> 
> You can also obtain segments that are backed by on-heap memory, by wrapping a segment around a Java array. E.g. doing MemorySegment.ofArray(new int[200]). If you do that, the resulting segment will have a non-empty array.
> 
> Since in your case you are working with off-heap memory (otherwise you wouldn't be able to exchange data with native functions), it is normal for the segment backing array to be null/empty, given that the memory segment is backed by a region of memory that resides off the Java heap.
> 
> I hope this helps.
> 
> Maurizio
> 

Very completely explained. Possibly not completely understood yet. But hopefully will be as I continue. 

Thanks again.