Idea: Lazy upcasting

[Marcin Kuszczak]

> 
> How about:
> 
.....
> 
> That should already work.
> 
> Cheers,
> 
> Reiner

I put into my compiler:

interface Storage {
    Storage param1(int);
}

abstract class StorageImpl(T) : Storage {
    static assert(is(typeof(this) == T));

        T param1(int p1)
        {
                this.p1 = p1;
                return cast(T)this;
        }
        private int p1;
}

class SpecificStorage : StorageImpl!(SpecificStorage) {
        SpecificStorage param2(bool p2) {
                this.p2 = p2;
                return this;
        }
        private bool p2;
}

void main() {
        auto c = (new SpecificStorage).param1(4).param2(true);

        writefln(SpecificStorage.p1, " --- ", SpecificStorage.p2);

}


... and get errors using DMD 1.009 on Linux:
covariance.d(5): class covariance.StorageImpl!(SpecificStorage).StorageImpl
unable to resolve forward reference in definition
covariance.d(16): class covariance.SpecificStorage unable to resolve forward
reference in definition

Errors on declaration of "class StorageImpl(T)" and "class SpecificStorage". 

To say true I don't know why they appear - IMHO it should compile. Maybe
it's bug?


-- 
Regards
Marcin Kuszczak (Aarti_pl)
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