2 releases
0.2.1 | Sep 27, 2022 |
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0.2.0 | Sep 27, 2022 |
#137 in #tuple
Used in constdefault
8KB
71 lines
ConstDefault Trait
A Default
-like trait and derive macros for const
evaluation contexts.
This crate defines the ConstDefault
trait and implements it for
Rust primitives, prelude types, tuples and arrays. Furthermore it
provides a derive macro so that users can implement ConstDefault
easily for their custom types.
- 100% safe Rust
no_std
compatible- Full macro hygiene
- No dependencies
Usage
Add
[dependencies]
constdefault = { version = "1.0", features = ["derive"] }
to your Cargo.toml
to start using it.
Examples
Rust Primitives
use constdefault::ConstDefault;
fn main() {
assert_eq!(<i32 as ConstDefault>::DEFAULT, 0);
assert_eq!(<Option<i32> as ConstDefault>::DEFAULT, None);
assert_eq!(<String as ConstDefault>::DEFAULT, String::new());
assert_eq!(<Vec<u8> as ConstDefault>::DEFAULT, Vec::new());
}
Derive
use constdefault::ConstDefault;
#[derive(ConstDefault, Debug, Default, PartialEq)]
pub struct Color {
r: u8,
g: u8,
b: u8,
}
fn main() {
assert_eq!(
<Color as ConstDefault>::DEFAULT,
Color::default(),
);
}
Dependencies
~1.5MB
~35K SLoC