# derive(TryFrom, From)

This library provides convenient derive macros for the standard library's [`std::convert::TryFrom`](https://doc.rust-lang.org/std/convert/trait.TryFrom.html) and [`std::convert::From`](https://doc.rust-lang.org/std/convert/trait.From.html) traits.

## Example

```toml
[dependencies]
try-from-discrim = "1.0"
```

and then:

```rust
#[macro_use] extern crate try_from_discrim;

#[derive(TryFrom)]
#[from(u8)]
enum RegisterIndex {
	B = 0,
	C = 1,
	D = 2,
	E = 3,
	H = 4,
	L = 5,
	HlInd = 6,
	A = 7,
}
```

(You do not need the `extern crate` line with Rust 2018 or later.)

The discriminants can be omitted, too!
Check [the documentation](https://docs.rs/try-from-discrim) for more information.

## Details

- This crate intentionally stays out of your public API.
  The provided implementations are identical to as if you had written them by hand, thus switching from handwritten `impl`s to this crate or vice-versa is not a breaking change.
- Using the standard library conversion traits enables working with more code than deriving a custom trait instead.
- Non-exhaustive enums can still implement `From` using a fallback variant.

The generated implementations are compatible with a `#[no_std]` environment.

## License

This crate is licensed under the Mozilla Public License 2.0, see the LICENSE file.