What is the difference between Box and &Trait / Box?

Question

When writing code with traits you can put the trait in a trait bound:

use std::fmt::Debug;

fn myfunction1(v: Box) {
    println!(\"         


        

Answer 1

Importantly, you don't have to put the generic type behind a reference (like & or Box), you can accept it directly:

fn myfunction3(v: T) {
    println!("{:?}", v);
}

fn main() {
    myfunction3(5);
}

This has the same benefits of monomorphization without the downside of additional memory allocation (Box) or needing to keep ownership of the value somewhere (&).

I would say that generics should often be the default choice — you only require a trait object when there is dynamic dispatch / heterogeneity.