Re: How to do "inheritance" in D structs

[TheFlyingFiddle via Digitalmars-d-learn]

On Wednesday, 12 October 2016 at 01:22:04 UTC, lobo wrote:

Hi,

I'm coming from C++ and wondered if the pattern below has an equivalent in D using structs. I could just use classes and leave it up to the caller to use scoped! as well but I'm not sure how that will play out when others start using my lib.

Thanks,
lobo


module A;

class Base1 {
    int ival = 42;
}
class Base2 {
    int ival = 84;
}

module B;

class S(ABase) : ABase {
    string sval = "hello";
}

module C;

import A;
import B;

void main() {
    auto s= scoped!(S!Base1); // scoped!(S!Base2)
}

You could use "alias this" to simulate that type of inheritence.

module A;
struct Base1
{
    int ival = 42;
}

module B;

struct Base2
{
    int ival = 84;
}

module C;
import A, B;

struct S(Base) if(is(Base == struct))
{
    Base base;
    alias base this;
    string sval = "Hello ";
}

void foo(ref ABase base)
{
    base.ival = 32;
}

void main()
{
    S!Base1 a;
    S!Base2 b;
    writeln(a.sval, a.ival);
    writeln(b.sval, b.ival);
    foo(a);
    writeln(a.sval, a.ival);
}