dyn-hash 0.1.2

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

[<img alt="github" src="https://img.shields.io/badge/github-dtolnay/dyn--hash-8da0cb?style=for-the-badge&labelColor=555555&logo=github" height="20">](https://github.com/dtolnay/dyn-hash)
[<img alt="crates.io" src="https://img.shields.io/crates/v/dyn-hash.svg?style=for-the-badge&color=fc8d62&logo=rust" height="20">](https://crates.io/crates/dyn-hash)
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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<dyn MyTrait> can derive Hash:
#[derive(Hash)]
struct Container {
    trait_object: Box<dyn MyTrait>,
}
```

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 <https://doc.rust-lang.org/reference/items/traits.html#object-safety>
 --> $SYSROOT/lib/rustlib/src/rust/library/core/src/hash/mod.rs
  |
  |     fn hash<H: Hasher>(&self, state: &mut H);
  |        ^^^^ ...because method `hash` has generic type parameters
```

<br>

#### License

<sup>
Licensed under either of <a href="LICENSE-APACHE">Apache License, Version
2.0</a> or <a href="LICENSE-MIT">MIT license</a> at your option.
</sup>

<br>

<sub>
Unless you explicitly state otherwise, any contribution intentionally submitted
for inclusion in this crate by you, as defined in the Apache-2.0 license, shall
be dual licensed as above, without any additional terms or conditions.
</sub>