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

[NotYouAgain]

On Saturday, 27 April 2024 at 22:59:29 UTC, Steven Schveighoffer 
wrote:
> On Friday, 26 April 2024 at 23:42:48 UTC, NotYouAgain wrote:
>
>> I don't agree with any of those propositions.
>
> OK, and that is understandable. What I'm trying to convey is 
> that *this is a design decision*. You may not agree with it, 
> but it is not something that I think is "fundamental" to OO 
> programming.
>
> I don't need to continue this, I've said my piece, and I'm not 
> interested in further discussion on this. If you end up with a 
> more formal proposal I likely will argue against it, but no 
> hard feelings, I fully understand that there are certain points 
> of view that I don't agree with but that reasonable people will 
> think is correct or better.
>
> We can agree to disagree, and still be friends ;)
>
> -Steve

Actually, here is the fundamental problem:

D won't let me expression my intent in the code below. Had I 
wanted to express a const or an immutable (for example) I can 
express it - D won't stand in my way there. But if I want to 
something that the vast majority of class-oriented oop 
programmers would expect to, that is, declare a member in my 
class-type to 'actually' be private to that type, then D and all 
the usual naysayers that come out when this topic is raised, 
insist on standing in my way. No they say. You actually don't 
need to do that. But if you do, put the subclass in separate 
module. Put the unittest in their separate module as well.

So do you see the 'actual' problem here, or just the one you want 
to see?

That there is so much fierce opposition to such a simple 
proposition, has always been bewildering. The source of that 
opposition, is usually a hate for oop in general, a hate for oo 
programmers (e.g calling them oop..philes), a wish to see oop 
stripped complelely out of D, or an insistence that all 
class-oriented oo programmers change how they think, so that 
think the way D wants to them think (a form of mind coercion 
really).

The idea is that a class should have an option to have truly 
private member, is sound.

The oppostition is the fundamental problem.