pub trait LightClone: Clone {
// Provided methods
fn light_clone(&self) -> Self { ... }
fn lc(&self) -> Self { ... }
}Expand description
Marker trait for types that are O(1) to clone.
LightClone is a marker trait that asserts a type’s Clone implementation is cheap.
Cloning involves only:
- Atomic refcount increments (Arc)
- Non-atomic refcount increments (Rc)
- Bitwise copy (Copy types)
- Persistent data structure cloning (im, imbl, rpds)
This trait is similar to Facebook’s Dupe
crate but provides a .light_clone() method that delegates to clone().
§Usage
Prefer .light_clone() over .clone() when you want to make the cheap clone explicit:
use light_clone::LightClone;
let x: i32 = 42;
let y = x.light_clone(); // Explicit: this is a light clone
assert_eq!(x, y);A shorthand .lc() method is also available:
use light_clone::LightClone;
let x: i32 = 42;
let y = x.lc(); // Shorthand for light_clone()
assert_eq!(x, y);§Derive Macro
Use #[derive(Clone, LightClone)] on structs to get compile-time enforcement that all
fields are cheap to clone. The derive macro requires Clone to be implemented separately
(either via derive or manual impl) and generates a LightClone impl with bounds that
ensure all fields implement LightClone:
ⓘ
use light_clone::LightClone;
use std::sync::Arc;
#[derive(Clone, LightClone)]
struct Person {
id: i64,
name: Arc<str>,
}The compile-time enforcement comes from the generated bounds - if any field doesn’t
implement LightClone, compilation will fail.
Provided Methods§
Sourcefn light_clone(&self) -> Self
fn light_clone(&self) -> Self
Returns a light clone of the value.
This operation is guaranteed to be O(1), involving only:
- Atomic or non-atomic refcount increments
- Bitwise copies for Copy types
The default implementation simply calls clone(), which is correct for all
LightClone types since their Clone is guaranteed to be O(1).
Sourcefn lc(&self) -> Self
fn lc(&self) -> Self
Shorthand for light_clone().
Dyn Compatibility§
This trait is not dyn compatible.
In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.