Describing what they are may be too hard for a HN comment, but what they achieve is easier. Traits are the way Rust supports both dynamic dispatch and static di

Describing what they are may be too hard for a HN comment, but what they achieve is easier. Traits are the way Rust supports both dynamic dispatch and static dispatch in polymorphic functions. C++ supports both kinds of dispatch too, but the means to achieve it are not the same across all scenarios. If you want to go from one to the other, you'll probably have to rewrite your code or create wrapper classes in C++. In Rust, you accept a &trait instead of constraining a generic type. C++ handles static dispatch through implicit template interfaces today, in the future by concept maps (but you can implement an ersatz version of it today, described in a blog post I wrote on this very topic[1]). Dynamic dispatch is always through your class's vtable. [1] http://chrisbranch.co.uk/2015/02/make-your-c-interfaces-trait-forward/ http://chrisbranch.co.uk/2015/02/make-your-c-interfaces-trai...