Crate sensible

This is a crate for a more configurable derive macro to derive an implementation for Default. Rust’s std::default module provides a derive implementation, but for structs, it requires that:

• Every member on the struct implement Default.
• Every member on the struct must use the Default implementation.

This is fine for many cases, but consider the case of a large struct where just one or two fields should default to something other than their type’s Default implementation: now you have to implement the whole thing.

sensible provides a configurable derive macro that allows giving certain fields alternate default values.

Example

use sensible::Default;

#[derive(Default)]
struct Foo {
  a: u32,  // default value: 0

  #[default(42)]
  b: u32,  // default value: 42
}

Derive Macros

Default

Derive a std::default::Default implementation, using customized values where provided.