#fallback #helper #derive #mechaism #fallback-spec

macro fallback-derive

A helper library to implement fallback mechaism

3 releases

0.1.2 Jan 13, 2024
0.1.1 Mar 21, 2023
0.1.0 Sep 10, 2022

#24 in #fallback

Download history 37/week @ 2023-11-30 37/week @ 2023-12-07 134/week @ 2023-12-14 100/week @ 2023-12-21 22/week @ 2023-12-28 30/week @ 2024-01-04 35/week @ 2024-01-11 17/week @ 2024-01-18 9/week @ 2024-01-25 36/week @ 2024-02-01 35/week @ 2024-02-08 47/week @ 2024-02-15 93/week @ 2024-02-22 36/week @ 2024-02-29 35/week @ 2024-03-07 33/week @ 2024-03-14

203 downloads per month
Used in 5 crates (via fallback)

MIT license

7KB
108 lines

fallback

This is a helper library to implement fallback mechaism. It contains two Option, and if the "desired" one is None, the "base" one will be chosen.

A trait called FallbackSpec is used to implement field fallback for a struct.

use fallback::*;

#[derive(FallbackSpec)]
struct Foo {
    data1: i32,
    data2: String,
}

let data = Foo {
    data1: 123,
    data2: "Hello".to_string(),
};

let data = Fallback::new(None, Some(data));
let data = data.spec();

assert_eq!(data.data1.unzip(), (None, Some(123)));
assert_eq!(data.data2.unzip(), (None, Some("Hello".to_string())));

Dependencies

~330–780KB
~19K SLoC