Hey there, I’m currently learning Rust (coming from object-oriented and also to some degree functional languages like Kotlin) and have some trouble how to design my software in a Rust-like way. I’m hoping someone could help me out with an explanation here :-)

I just started reading the book in order to get an overview of the language as well.

In OOP languages, I frequently use design patterns such as the Strategy pattern to model interchangeable pieces of logic.

How do I model this in Rust?

My current approach would be to define a trait and write different implementations of it. I would then pass around a boxed trait object (Box<dyn MyTrait>). I often find myself trying to combine this with some poor man’s manual dependency injection.

This approach feels very object oriented and not native to the language. Would this be the recommended way of doing things or is there a better approach to take in Rust?

Thanks in advance!

    • hallettj@leminal.spaceEnglish
      2·
      3 months ago

      To expand on why generics are preferred, just in case you haven’t seen these points yet: the performance downsides of Box<dyn MyTrait> are,

      • methods use dynamic dispatch in this case
      • requires heap allocation

      There is also a possible type theory objection which is that normally there is a distinction between types and traits. Traits are not types themselves, but instead define sets of types with shared behavior. (That’s why the same feature in Haskell is called a “type class”, because it defines a class of types that have something in common.) But dyn turns a trait into a type which undermines the type/trait distinction. It’s useful enough to justify being in the language, but a little unsettling from a certain perspective.