smart-default 0.6.0

Rust custom-derive macro for Default with more control on the fields

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Rust SmartDefault

Custom derive for automatically implementing the Default trait with customized default values:

extern crate smart_default;

enum Foo {
    Baz {
        #[default = 12]
        a: i32,
        b: i32,
        c: Option<i32>,
        #[default(_code = "vec![1, 2, 3]")]
        d: Vec<u32>,
        #[default = "four"]
        e: String,

assert!(Foo::default() == Foo::Baz {
    a: 12,
    b: 0,
    c: Some(0),
    d: vec![1, 2, 3],
    e: "four".to_owned(),

Requires Rust 1.30+ (for non-string values in attributes)