Extending D's support for object-oriented design with private(this)

[NotYouAgain]

On Saturday, 27 April 2024 at 02:03:35 UTC, Richard (Rikki) 
Andrew Cattermole wrote:
> On 27/04/2024 11:50 AM, NotYouAgain wrote:
>> On Friday, 26 April 2024 at 16:38:54 UTC, Steven Schveighoffer 
>> wrote:
>>> ...
>>> module m;
>>>
>>> class C
>>> {
>>>    private(this) int _count;
>>>    public void setCount(int c) { _count = c; }
>>>
>>>    unittest
>>>    {
>>>       C c = new C();
>>>       c._count = 42; // oops, this is still allowed
>>>    }
>>> }
>>> ```
>> 
>> There is no 'oops' there.
>> 
>> The unittest is a member of the class!
>> 
>> It the unittest outside of the class that should not be 
>> allowed to compile.
>
> Based on the fact that a unittest block does not have a this 
> pointer, Steven is correct. It isn't part of the scope.
>
> If you want this you have to be specific that it is included 
> (and yes this is an example of why a DIP is needed to know what 
> your assumptions are).

No I don't understand.

The unittest is a special function being declared inside the 
scope of the class type. I would entirely expect it to have 
access to all private members of that type.

When the unittest is declared outside the scope of the function, 
I would expect it to NOT have access to the private(this) members 
of the type.

That's exactly what I expect and exactly how it works in OpenD.

I presume it's a static function? Hence no this pointer? (I 
really don't know how its implemented, nor do I care. I can only 
care that it works as I expect it to work in OpenD.