Programming Rust, 2nd Edition

Chapter 13. Utility Traits

Science is nothing else than the search to discover unity in the wild variety of nature—or, more exactly, in the variety of our experience. Poetry, painting, the arts are the same search, in Coleridge’s phrase, for unity in variety.

Jacob Bronowski

This chapter describes what we call Rust’s “utility” traits, a grab bag of various traits from the standard library that have enough of an impact on the way Rust is written that you’ll need to be familiar with them in order to write idiomatic code and design public interfaces for your crates that users will judge to be properly “Rustic.” They fall into three broad categories:

Language extension traits

Just as the operator overloading traits we covered in the previous chapter make it possible for you to use Rust’s expression operators on your own types, there are several other standard library traits that serve as Rust extension points, allowing you to integrate your own types more closely with the language. These include Drop, Deref and DerefMut, and the conversion traits From and Into. We’ll describe those in this chapter.

Marker traits

These are traits mostly used to bound generic type variables to express constraints you can’t capture otherwise. These include Sized and Copy.

Public vocabulary traits

These don’t have any magical compiler integration; you could define equivalent traits in your own code. But they serve the important goal of setting down conventional solutions for common problems. These ...