I have a struct that has struct data member and I'd like to forward some (not all) functions from internal data member. Some thing like this:

struct A {
    void foo() const { writeln("A.foo"); }
}

struct B {
    A a;

    auto foo(ARGS...)(ARGS args) { return a.foo(args); }
    // alias foo = a.foo;
}

void main()
{
    B b;
    b.foo();   // In "alias" case: Error: `this` for `foo` needs to be type `A` not type `B`
}

Is there simpler way to achieve this?
I tried alias foo = a.foo but it doesn't work: "Error: this for foo needs to be type A not type B" - when function is called (b.foo()).

Another question: does auto foo(ARGS...)(ARGS args) { return a.foo(args); } correctly forward ref, const etc. arguments?

On Thursday, 17 February 2022 at 20:59:43 UTC, Andrey Zherikov wrote:

Actually the answer is NO. I have to do auto foo(ARGS...)(auto ref ARGS args) { return a.foo(args); }. Also if a.foo is a const function then I have to add const to this definition as well.

On Thursday, 17 February 2022 at 21:17:02 UTC, Andrey Zherikov wrote:

This also doesn't forward correctly. It'll always try to copy all arguments. What would fowrard is

import core.lifetime : forward;

auto foo(Args...)(auto ref Args args) { return a.foo(forward!args); }