Child struct lifetime is bounded by its Parent struct lifetime

Question

Currently, I have a code where I need that Child struct have a reference to field 'x' of its Parent struct. For those needs I did workaround with using Rc<>.

  #[derive(Clone)]
  pub struct SomeBigStruct {
    pub value: u32,
    // ... plus many vector properties
  }
  
  pub struct ParentV1 {
    pub x: SomeBigStruct,
    pub children: Vec<ChildV1>,
  }

  pub struct ChildV1 {
    pub x_ref: Rc<SomeBigStruct>,
  }

  fn new_parent_v1() -> ParentV1 {
    let x = SomeBigStruct{value: 42};
    let x_ref = Rc::new(x.clone());
    ParentV1 {
      x,
      children: vec![
        ChildV1 { x_ref: x_ref.clone() },
        ChildV1 { x_ref: x_ref.clone() },
        //... plus thousands of another children
      ],
    }
  }

This works, but I was wondering that simple reference with lifetime should be also feasible. Because lifetime of struct which I want to refer is known (same as Parent struct lifetime). Something like:

  pub struct ParentV2 {
    pub x: SomeBigStruct,
    pub children: Vec<ChildV2<'lifetime_of_parent_struct>>,
  }

  pub struct ChildV2<'a> {
    pub x_ref: &'a SomeBigStruct,
  }

  fn new_parent_v2<'a>() -> ParentV2<'a> {
    let x = SomeBigStruct{value: 42};
    ParentV2 {
      children: vec![
        ChildV2 { x_ref: &x },
        ChildV2 { x_ref: &x },
      ],
      x,
    }
  }

This of course cannot be compiled because I do not know how define reference only to Parent struct lifetime. Is it even possible? If not is there any better workaround than mine? Thanks.

Child struct lifetime is bounded by its Parent struct lifetime

0 Answers0