nested inout return type

[Simon Bürger via Digitalmars-d-learn]

On Tuesday, 14 June 2016 at 14:47:11 UTC, Steven Schveighoffer 
wrote:
>> * only do one mutable version of opSlice
>> * add implicit cast (using "alias this") for const(Slice!T) ->
>> Slice!(const(T)).
>
> Interesting, but unfortunately, the compiler isn't eager about 
> this conversion. auto x = s[5 .. 7] isn't going to give you a 
> Slice!(const(T)), like an array would. But I like the idea.

Hm, you are right, in fact it doesn't work. Somehow it seemed to 
in my usecase. Well, triplicate it is then. Which isn't that bad 
using something like

auto opSlice(size_t a, size_t b)
{
    // actual non-trivial code
}

auto opSlice(size_t a, size_t b) const
{
    return Slice!(const(T))(ptr, length).opSlice(a,b);
}

auto opSlice(size_t a, size_t b) immutable
{
    return Slice!(immutable(T))(ptr, length).opSlice(a,b);
}