Re: tuple parameter fwd

[kdmult]

On Tuesday, 6 August 2013 at 09:53:33 UTC, Ali Çehreli wrote:

Do you mean that when P[0] is already an instance of A, then R should be P[0]. Otherwise, R should be A!P? If so, the following works:

class A(P...)
{
    pragma(msg, "\nA: " ~ P.stringof);
}

class BImpl(R, P...)
{
    pragma(msg, "R: " ~ R.stringof ~ ", P: " ~ P.stringof);
}

template B(P...)
{
    static if (is (P[0] == A!U, U)) {

/* The first type is already an A instance. Accept the types as is. */

        alias B = BImpl!P;

    } else {
        /* The first type is not an A instance. Inject one. */
        alias B = BImpl!(A!P, P);
    }
}

void main()
{
    auto b0 = new B!(int, double, char);
    auto b1 = new B!(A!long, int, double);
}

Ali

Great! Thanks Ali.