Hash trait that is object-safe ============================== [

](https://github.com/dtolnay/dyn-hash) [

](https://crates.io/crates/dyn-hash) [

](https://docs.rs/dyn-hash) [

](https://github.com/dtolnay/dyn-hash/actions?query=branch%3Amaster) This crate provides a `DynHash` trait that can be used in trait objects. Types that implement the standard library's [`std::hash::Hash`] trait are automatically usable by a `DynHash` trait object. [`std::hash::Hash`]: https://doc.rust-lang.org/std/hash/trait.Hash.html ## Example ```rust use dyn_hash::DynHash; trait MyTrait: DynHash { /* ... */ } // Implement std::hash::Hash for dyn MyTrait dyn_hash::hash_trait_object!(MyTrait); // Now data structures containing Box can derive Hash: #[derive(Hash)] struct Container { trait_object: Box, } ``` Without the dyn-hash crate, a trait `trait MyTrait: std::hash::Hash {...}` would not be object-safe (`dyn MyTrait`). ```console error[E0038]: the trait `MyTrait` cannot be made into an object --> src/main.rs:7:12 | 7 | let _: &dyn MyTrait; | ^^^^^^^^^^^^ `MyTrait` cannot be made into an object | note: for a trait to be "object safe" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit --> $SYSROOT/lib/rustlib/src/rust/library/core/src/hash/mod.rs | | fn hash(&self, state: &mut H); | ^^^^ ...because method `hash` has generic type parameters ```
#### License ^{Licensed under either of Apache License, Version
2.0 or MIT license at your option.}
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