Miss Dada  🏳️‍⚧️

Wait, but that's consistent. Box<T> where T: Trait doesn't implement Trait. Box<dyn T> doesn't either. Both pass methods down.

I think you've misunderstood "Box<dyn Trait> doesn't automatically implement Trait": that is true, but you can still call the trait methods the way you can with Box<T>

oh, because the method calls pass down to the Box contents... okay then I need to better understand what "Box implementing a trait" means, hopefully these new boxed closure features will tell me!

but also, someone told me you can impl a trait for another trait, rather than for all types that implement said trait, i.e. `impl Trait for Other` rather than `impl<T: Other> Trait for T` and I still don't know what that means or if it's relevant here

That's the same as `impl Trait for dyn Other` (`dyn` is optional, it's an idiom for marking a trait in a type position to mark it as dynamically dispatched). You're implementing the trait only for trait objects of type Other

ah so only for &dyn Other, Box<dyn Other>, etc, but not for any T: Other ?

well, to be precise, it implements it for one type: `dyn Other`. &dyn Other, Box<dyn other> get it through deref, but they do not get the trait implemented

Box<dyn Other> and &dyn Other are not T: Other, as I mentioned before. They get Other methods through deref. Some traits (eg. Fn*) may choose to blanket implement themselves on these types.