class A {

    string str;

}

​

class B {

    string str;

    A a = new A();

    //this() { a = new A(); } //works if activated

}

​

void main() {

    B b = new B();

    b.a.str = "of A";

    b.str = "of B";

​

    B c = new B();

    assert( c.a.str == "" ); //why no re-init?

    assert( c.str == "" );

}

​