Crate impl_tools

Impl-tools

Autoimpl

#[autoimpl] is a variant of #[derive], supporting:

• explicit generic parameter bounds
• ignored fields
• traits defined using a primary field
• generic re-implementations for traits

#[autoimpl(for<'a, T: trait + ?Sized> Box<T>)]
// Generates: impl<'a, T: trait + ?Sized> Animal for Box<T> { .. }
trait Animal {
    fn number_of_legs(&self) -> u32;
}

#[autoimpl(Debug ignore self.animal where T: Debug)]
// Generates: impl<T, A: Animal> std::fmt::Debug for Named<A> where T: Debug { .. }
#[autoimpl(Deref, DerefMut using self.animal)]
// Generates: impl<T, A: Animal> std::ops::Deref for Named<A> { .. }
// Generates: impl<T, A: Animal> std::ops::DerefMut for Named<A> { .. }
struct Named<T, A: Animal> {
    name: T,
    animal: A,
}

fn main() {
    struct Fish;
    impl Animal for Fish {
        fn number_of_legs(&self) -> u32 {
            0
        }
    }

    let my_fish = Named {
        name: "Nemo",
        animal: Box::new(Fish),
    };

    assert_eq!(
        format!("{my_fish:?} has {} legs!", my_fish.number_of_legs()),
        r#"Named { name: "Nemo", .. } has 0 legs!"#
    );
}

Attribute Macros

autoimpl

A variant of the standard derive macro