1. use std::ops::Deref;
    3. struct A(usize);
    4. struct B(usize);
    6. impl A {
    7.     fn aaa(&self) { println!("A: {}", self.0); }
    8. }
    10. struct C {
    11.     a: A,
    12.     b: B,
    13. }
    15. impl Deref for C {
    16.     type Target = A;
    17.     fn deref(&self) -> &Self::Target { &self.a }
    18. }
    20. fn main() {
    21.     let o = C { a: A(1), b: B(2) };
    22.     o.aaa();
    23. }