trait-variant 0.0.1

Utilities for working with impl traits in Rust.

trait_variant

trait_variant generates a specialized version of a base trait that uses async fn and/or -> impl Trait. For example, if you want a Sendable version of your trait, you'd write:

#[trait_variant::make(IntFactory: Send)]
trait LocalIntFactory {
    async fn make(&self) -> i32;
    // ..or..
    fn stream(&self) -> impl Iterator<Item = i32>;
    fn call(&self) -> u32;
}

Which creates a new IntFactory: Send trait and additionally bounds IntFactory::make(): Send and IntFactory::stream(): Send. Ordinary methods are not affected.

Implementers of the trait can choose to implement the variant instead of the original trait. The macro creates a blanket impl which ensures that any type which implements the variant also implements the original trait.

License and usage notes

Licensed under either of Apache License, Version 2.0 or MIT license at your option.