What is the representation for a type like Box<Reader+Writer>? Is there an extra... | Hacker News

Hacker Newsnew | past | comments | ask | show | jobs | submit

		kalmar on May 12, 2015 \| parent \| context \| favorite \| on: Abstraction without overhead: traits in Rust What is the representation for a type like Box<Reader+Writer>? Is there an extra indirection to get each of the vtables? Is there synthesized combined trait type and just one vtable pointer?

Jweb_Guru on May 12, 2015 [–]

I am pretty sure you can't actually construct such a type (at least not at the moment) so Rust sort of sidesteps the question.

Manishearth on May 12, 2015 | [–]

IIRC you can.

Rusky on May 12, 2015 | | [–]

I get this when I try something like `as Box<Read+Write>`

    error: only the builtin traits can be used as closure or object bounds [E0225]

Manishearth on May 12, 2015 | | [–]

TIL; thanks :)

Guidelines | FAQ | Lists | API | Security | Legal | Apply to YC | Contact