Newtype Variant Conversions

Rust macro crate to automatically generate conversions from variant types into the target enum.

This crate requires Rust 1.15 or above to compile on stable.

Examples

#[macro_use]
extern crate from_variants;

#[derive(Debug, Clone, PartialEq, Eq, FromVariants)]
pub enum Lorem {
    Str(String),
    Num(u16),
}

fn main() {
    assert_eq!(Lorem::Num(10), Lorem::from(10));
}

You can skip variants to avoid type collisions:

#[macro_use]
extern crate from_variants;

#[derive(Debug, Clone, PartialEq, Eq, FromVariants)]
pub enum Ipsum {
    Hello(String),
    
    #[from_variants(skip)]
    Goodbye(String),
}

fn main() {
    assert_eq!(Ipsum::Hello("John".to_string()), Ipsum::from("John".to_string()));
}

Features

• Variant opt-out: To skip a variant, add #[from_variants(skip)] to that variant.
• Conversion support: Use #[from_variants(into)] at the enum or variant level to get a generated conversion that accepts Into<VariantType>. In practice, this will only work with types defined in the same crate; otherwise you'll get conflicting impl errors.
• no_std support: Generated conversions do not depend on the standard library.