Construct enum variants from their discriminant
NOTE: I'm no longer maintaining this due to the existence of soccer; I've pretty much absorbed what I built here into that new crate, which I'll be maintaining from now on. If this crate looks interesting to you, you should go use soccer instead (it's better, I promise).
In order to initialize certain enum values from their discriminant, you basically have to manually write a giant match block that maps from each discriminant to the corresponding variant. This is both an annoyingly manual process and a potentially unsafe one; for example, what if you forget to update a discriminant value in the match after changing it in the enum definition?
This crate addresses that by providing a way to automatically generate that initialization code. More specifically, for fieldless, non-generic enums with a #[repr(...)] specified, it provides the FromDiscriminant trait and corresponding derive macro that automatically generates the initialization code as an implementation of the trait.
This project is licensed under the MIT License.
A simple example, based on the use case that inspired this crate to begin with: ```rust use discrim::FromDiscriminant;
enum Opcode { Add, Sub, Mul, Div, }
fn main() { // prints "Ok(Mul)" println!("{:?}", Opcode::from_discriminant(2));
// prints "Err(5)"
println!("{:?}", Opcode::from_discriminant(5));
} ```