An optional/maybe type with range semantics

[aliak]

On Tuesday, 27 February 2018 at 11:58:34 UTC, Dukc wrote:
> On Monday, 26 February 2018 at 20:04:14 UTC, aliak wrote:
>> Guess I could do a pointer and call new when i need to store a 
>> value instead. Or maybe it's better to do it like above and 
>> store as value type with default value and a boolean at the 
>> site. Not sure.
>
> You do not need a separate boolean field. If someone assigns 
> "none" or calls popFront() just assign the pointer to null. 
> When someone queries empty, you check whether the pointer 
> points to null.  The default value is easy too: 
> typeof(element).init.

Either you misunderstood or my writing was not clear. I meant 
you'd need a boolean if you were using a value type (was just 
speaking out loud as another alternative to a pointer or array)

>
> That's the superior design, because it does not need any excess 
> memory for the empty flag.

It means using new, so not sure how superior it is compare to 
storing a value type.