UFCS

main.d

import mod;

struct Public {
    int oops() {
        return 42;
    }
}

struct Nope {

}

int oops(T)(T obj) {
    return 33;
}

void main() {
    auto pub = Public();
    auto nop = Nope();
    assert(pub.oops == 42);
    assert(nop.oops == 33);
}

mod.d

struct Private {
    private int oops() {
        return -1;
    }
}