better-default-derive

A better std::default::Default macro.

Supports:

• Struct
  • Unit
  • Named
  • Unnamed
  • Generic
• Enum
  • Unit
  • Named
  • Unnamed
  • Generic

Usage

[dependencies]
better-default-derive = "0.1.0"

use better_default_derive::Default;

#[derive(Debug, PartialEq, Eq, Default)]
enum Either<L, R> {
    Left(L),
    #[default]
    Right(R),
}

fn main() {
    let either: Either<String, u8> = Either::default();
    assert_eq!(either, Either::Right(u8::default()));
}

Comparison to other libraries

educe

Advantages:

• Support several built-in traits.
• More popular.

Disadvantages:

• Not a drop-in replacement of the std.
• Slower compile times.

Roadmap

• Better error message when a field is missing the Default instance.

• Support union types

• Support associated types

  use better_default_derive::Default;
  
  pub trait Trait {
      type Value;
  }
  
  #[derive(Default)]
  pub struct Field<T: Trait> {
      values: Vec<T::Value>,
  }