`restricted` member variables

[user1234]

On Wednesday, 22 June 2022 at 23:08:38 UTC, deadalnix wrote:
> On Wednesday, 22 June 2022 at 21:30:07 UTC, forkit wrote:
>> I refer maxhaton back to the seminal paper on the benefits of 
>> abstract data types:
>>
>> Programming with abstract data types - Liskov and Zilles 1974
>>
>> https://dl.acm.org/doi/pdf/10.1145/942572.807045
>
> I wish you understood that every comment that you make where 
> you fail to present any concrete instance of the problem caused 
> weakens your case.
>
> Assuming the people you are talking to are not well versed in 
> the concept of asbtract data types is somewhat amusing, but I'm 
> afraid, also playing against your case.

to be fair, I think that, to any example presented here, the 
answer will be "put the aggregate declaration in its own module". 
But let's try something simple:

```d
struct VLA {
private:
     void* ptr;
     size_t length;
public:
     void setLength(size_t value);
}

struct Other {
     VLA vla;
     void imBad() {
         length += 1; // now I may have faults or not when reading 
the vla
     }
}
```

It's about being strict with yourself. What if I'm not really 
good, make stupid mistakes ? Now I have a security barrier, I can 
use `private(this)`, the compiler helps me with an error.