gistfile1.rs

struct Base<T: Derived> {
  x: u32,
  
  derived: T
}

trait Derived {
  fn foo_the_bars(&mut self, base: &mut Base) -> u32;
}

struct SomeDerived {
  y: u32
}

impl Derived for SomeDerived {
  fn foo_the_bars(&mut self, base: &mut Base) -> u32 {
    self.y += 1;
    
    base.x + self.y
  }
}

impl Derived for Box<Derived> {
  fn foo_the_bars(&mut self, base: &mut Base) -> u32 {
    **self.foo_the_bars(base)
  }
}