[seanmcdirmid]

There are multiple meanings of traits flying around in different languages. Some traits are type classes (Rust), some traits are mixins (Scala). The former are not really related to class-based inheritance, while the latter most definitely is (linearized multiple inheritance as defined by Cook & Bracha, not the mixins of CommonLisp). Self and smalltalk style traits are even more different.

[qznc]

Don't forget C++ traits, which are more like a design pattern.