social.noyu.me

I don’t know who needs to hear this, but

trait FooBar: Any {
  fn as_any(&self) -> &dyn Any {
    &self as &dyn Any
  }
}

sadly will not work, no matter how many apostrophes you add. you also can’t just call .downcast_ref() on a FooBar.

previously, when having to do this, i just gave up.

but it turns out there’s a practical workaround:

trait FooBar: Any {}
pub trait AnyFooBar {
    fn as_any<'a>(&'a self) -> &'a (dyn std::any::Any + 'static);
}   
impl<T: FooBar> AnyFooBar for T {
    fn as_any<'a>(&'a self) -> &'a (dyn std::any::Any + 'static) {
        &*self
    }   
}

I hope this helps avoid suffering for someone else!