A trait with a default method in Rust
Rust interview exercise on Traits & Generics, difficulty 2 of 3. Solve it in the editor beside a worked example, or cold in Interview mode with the example hidden; the tests run the moment you do.
Finish the Summary trait. summarize() has a default body: "(Read more from <author>...)". A Tweet's author is "@" plus its username, and it overrides summarize() with "<author>: <content>". An Article's author is its byline, and it keeps the default. Then write notify(item) for anything that implements Summary: "Breaking! <summary>".
Each exercise pairs a worked example with a twin problem to solve in a real editor; the tests run the moment you do. Interview mode hides the example: solve it from memory, without the hint or the solution, and it counts as solved cold. Progress is saved in your browser, and in your account if you sign in.