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

[NotYouAgain]

On Thursday, 25 April 2024 at 08:08:40 UTC, Dom DiSc wrote:
> On Thursday, 25 April 2024 at 06:05:23 UTC, zjh wrote:
>>
>> This improvement has no `side effects` on the `d` language. I 
>> really don't know why they `oppose` it?
>
> Opposition was only because of "friend"s, which destroys 
> encapsulation in an unpredictable manner. As long as no 
> "friend" attribute is proposed, everything is fine. Already 
> works without problems in OpenD.

If my understanding is correct, the concern was not about 
'friends' but 'C++ like' friends.
That is, friends that could essentially be anywhere.....and 
difficult to track down.

But D also has a 'friends' notion, implicately. That is, all code 
in the module is essentially a friend of any class in the module, 
and within a package of modules, that notion extends further. 
It's implicit in D, because the module is the unit of 
encapsulation, not the class.

So I'd say that D understands the necessity for a friend feature 
- it just restricts the borders of its use (i.e. to the module, 
or a package of modules).

This idea never involved the concept of 'C++ like' friends, nor 
would it even be needed, since a more suitably 'constrained 
border' for friendship is already in D - i.e. the module (or 
modules within a package).

And yes, I'm not aware of any problems using this feature that is 
already in OpenD ;-)