#fallback

fallback

A helper library to implement fallback mechaism

2 releases

0.1.1 Sep 23, 2022
0.1.0 Sep 10, 2022

#573 in Data structures

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412 downloads per month
Used in 4 crates (2 directly)

MIT license

9KB
159 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())));

lib.rs:

A fallback type.

[Fallback] type provides functionality to fallback if a value or a part of value doesn't exist.

Dependencies

~0.7–1MB
~26K SLoC