Crate enum_primitive

This crate exports a macro enum_from_primitive! that wraps an enum declaration and automatically adds an implementation of num::FromPrimitive (reexported here), to allow conversion from primitive integers to the enum. It therefore provides an alternative to the built-in #[derive(FromPrimitive)], which requires the unstable std::num::FromPrimitive and is disabled in Rust 1.0.

The current implementation requires all variants of the num to have an explicit discriminator value. This restriction may be relaxed in future versions.

Example

#[macro_use] extern crate enum_primitive;
extern crate num;
use num::FromPrimitive;

enum_from_primitive! {
#[derive(Debug, PartialEq)]
enum FooBar {
    Foo = 17,
    Bar = 42,
}
}

fn main() {
    assert_eq!(FooBar::from_i32(17), Some(FooBar::Foo));
    assert_eq!(FooBar::from_i32(42), Some(FooBar::Bar));
    assert_eq!(FooBar::from_i32(91), None);
}

Macros

enum_from_primitive!	Wrap this macro around an enum declaration to get an automatically generated implementation of num::FromPrimitive.
enum_from_primitive_impl!	Helper macro for internal use by enum_from_primitive!.
enum_from_primitive_impl_ty!	Helper macro for internal use by enum_from_primitive!.

Traits

FromPrimitive

A generic trait for converting a number to a value.