Ah ok, I'm back to being confused again then! Is this right: If Foo is a struct then Box<Foo> is static dispatch. If Foo is a trait Box<dyn Foo> is dynamic di

Ah ok, I'm back to being confused again then! Is this right: If Foo is a struct then Box<Foo> is static dispatch. If Foo is a trait Box<dyn Foo> is dynamic dispatch, but then so is Box<Foo> - but that is the regrettable point. So from now on, if Foo is a trait we should be writing Box<dyn Foo>, which is largely syntactic sugar to make the situation more clear? I don't fully understand what the release notes are saying about using impl Trait. When would you use Box<impl Foo> vs Box<dyn Foo>?