min-specialization

Rust's specialization feature allows you to provide a default implementation of a trait for generic types and then specialize it for specific types. This feature is currently unstable and only available on the nightly version of Rust.

This crate emulates Rust's #[feature(min_specialization)] unstable feature on stable Rust.

Example

# use min_specialization::specialization;
#[specialization]
mod inner {
    #[allow(unused)]
    trait Trait<U> {
        type Ty;
        fn number(_: U) -> Self::Ty;
    }

    impl<T, U> Trait<U> for T {
        type Ty = usize;
        default fn number(_: U) -> Self::Ty {
            0
        }
    }

    impl<U> Trait<U> for () {
        fn number(_: U) -> Self::Ty {
            1
        }
    }
}

see tests for more.