gistfile1.rs

use std::cell::RefCell;
 
struct Context {
data: RefCell<i32>;
}
 
struct A<'a> {
context: &'a Context,
}
 
struct BiggerContext<'a> {
priv context: &'a Context,
priv a: A<'a>,
}

impl Drop for BiggerContext {
  fn drop(self) {
    unsafe {
      let ctx: ~Context = cast::transmute(self.context)
    }
  }
}

fn create_bigger_context<'a>() -> ~BiggerContext<'a> {
  unsafe {
    let ctx : &'a Context = cast::transmute(~Context { RefCell::new(0) });
    BiggerContext { ctx, A { ctx }}
  }
}

impl BiggerContext<'a> {
  fn context(ctx: &'a self) -> &'a Context<'a> {
    ctx.context
  }

  fn A(ctx: &'a self) -> &'a A<'a> {
    unsafe {
      cast::transmute(&ctx.a)
    }
  }
}

gistfile2.rs

use std::cell::RefCell;
 
struct Context {
data: RefCell<i32>;
}
 
struct A<'a> {
context: &'a Context,
}
 
struct BiggerContext<'a> {
 context: &'a Context,
 a: A<'a>,
}

macro_rules! define_bigger_context(
  ($id: ident) => (
    let ctx = ~Context { RefCell::new(0) };
    let $id = BiggerContext { ctx, A { ctx }}
  );
)