• Mihail Lorenko (6/27) Feb 06 2020 Hello!
• Adam D. Ruppe (5/6) Feb 06 2020 A pointer to a class is a rare thing in B since they are already
• Mihail Lorenko (3/9) Feb 06 2020 Thanks for the answer!
• Steven Schveighoffer (12/21) Feb 06 2020 Not sure, but you might misunderstand. B is already a pointer in D (like...
• Steven Schveighoffer (3/4) Feb 06 2020 I meant, calls A.step;

Mihail Lorenko <miha.uva ya.ru> writes:

Hello!
Interested in a question.
Object "A" inherited object "B". And you need to return the 
object link "B". Is this possible in this language? Here is an 
example:

class B
{
    protected int a;
    public void step() {};
}

class A : B
{
    public override step()
    {
        import std.random;
        a = uniform(5,100);
    }
}

void main()
{
     B* b;
     A  a;
     a.step();
     b = a.B; //  FixMe: Here you need a link to object B from 
 object A.
}

Sorry to trouble you, thanks in advance!

Adam D. Ruppe <destructionator gmail.com> writes:

On Thursday, 6 February 2020 at 12:15:17 UTC, Mihail Lorenko 
wrote:
     B* b;


A pointer to a class is a rare thing in B since they are already 
automatic references. Just use `B b;` and ten `b = a` will just 
work.

Mihail Lorenko <miha.uva ya.ru> writes:

On Thursday, 6 February 2020 at 12:37:01 UTC, Adam D. Ruppe wrote:
 On Thursday, 6 February 2020 at 12:15:17 UTC, Mihail Lorenko 
 wrote:
     B* b;


 A pointer to a class is a rare thing in B since they are 
 already automatic references. Just use `B b;` and ten `b = a` 
 will just work.

Thanks for the answer!
Well, apparently I have to get around my problem. Thanks again!

Steven Schveighoffer <schveiguy gmail.com> writes:

On 2/6/20 8:05 AM, Mihail Lorenko wrote:
 On Thursday, 6 February 2020 at 12:37:01 UTC, Adam D. Ruppe wrote:
 On Thursday, 6 February 2020 at 12:15:17 UTC, Mihail Lorenko wrote:
     B* b;


 A pointer to a class is a rare thing in B since they are already 
 automatic references. Just use `B b;` and ten `b = a` will just work.

 
 Thanks for the answer!
 Well, apparently I have to get around my problem. Thanks again!

Not sure, but you might misunderstand. B is already a pointer in D (like 
Java, D's class instances are always references).

And derived classes implicitly cast to base classes. So the a.B syntax 
is not necessary.

To illustrate further:

A a = new A; // note, instances by default are null, you need to new them
B b = a; // implicit cast

assert(a is b); // they are the same object
b.step(); // virtual call, calls B.step

assert(a.a != 0); // note, protected allows access from same module.

-Steve

Steven Schveighoffer <schveiguy gmail.com> writes:

On 2/6/20 10:11 AM, Steven Schveighoffer wrote
 b.step(); // virtual call, calls B.step

I meant, calls A.step;

-Steve