Specified Default

specified_default_derive enables you to choose the defaults implemented by the Default trait. After it is derived, the object will behave exactly as it would had the standard Default trait been derived. Nested objects must implement either SpecifiedDefault or Default.

If you don't provide an override, the existing default value for that type will be used.

Getting Started

Add this crate to your Cargo.toml and ensure you add the #[macro_use] attribute when declaring this crate in main.rs/lib.rs.

Usage

Take a look at the tests for the different override combinations that are supported. The simplest usage would be:

#[derive(SpecifiedDefault)]
struct MyStruct {
    #[default = "640"]
    width: u32,
    #[default = "480"]
    height: u32,

    scenes: u32,
}

let result = MyStruct::default();

assert_eq!(result.width, 640);
assert_eq!(result.height, 480);
assert_eq!(result.scenes, 0);

// Or for enums...

#[derive(Debug, PartialEq, SpecifiedDefault)]
enum MyEnum {
    Foo,

    #[default]
    Bar,
}

assert_eq!(MyEnum::default(), MyEnum::Bar);