ambassador

ambassador is the most general-purpose Rust trait delegation crate (2.3M+ downloads). It delegates trait implementations via #[delegatable_trait] and #[derive(Delegate)], working for both structs (delegating to fields) and enums (delegating to variants), with cross-crate and generic support.

Compared to enum-dispatch (which is same-crate only with poor IDE support), ambassador trades a small amount of macro complexity for significantly broader applicability. For method-level delegation rather than whole-trait delegation, delegate (22.7M+) offers finer control with parameter modifiers like #[into], #[as_ref], and #[newtype]. See rust-enum-crates for the full dispatch landscape.