enum-repr

Derive enum repr conversions compatible with type aliases. Works on no_std.

EnumRepr proc macro takes an EnumReprType argument and defines two functions for the enum derived on: fn repr(&self) -> EnumReprType and fn from_repr(x: EnumReprType) -> Option<Self>. The real enum discriminant still remains isize.

```rust

[macrouse] extern crate enumrepr;

extern crate libc;

use libc::*;

[derive(Debug, PartialEq)]

[derive(EnumRepr)]

[EnumReprType = "c_int"]

pub enum IpProto { IP = IPPROTOIP as isize, IPv6 = IPPROTOIPV6 as isize, // … }

fn main() { asserteq!(IpProto::IP.repr(), IPPROTOIP); asserteq!(IpProto::fromrepr(IPPROTOIPV6), Some(IpProto::IPv6)); assert!(IpProto::fromrepr(12345).is_none()); } ```