1.0.0[−][src]Trait core::clone::Clone

[+] Show declaration

[+] Expand attributes
#[lang = "clone"]
pub trait Clone: Sized {
[+] Expand attributes
#[must_use = "cloning is often expensive and is not expected to have side effects"]
    fn clone(&self) -> Self;

    fn clone_from(&mut self, source: &Self) { ... }
}

[−]

A common trait for the ability to explicitly duplicate an object.

Differs from Copy in that Copy is implicit and extremely inexpensive, while Clone is always explicit and may or may not be expensive. In order to enforce these characteristics, Rust does not allow you to reimplement Copy, but you may reimplement Clone and run arbitrary code.

Since Clone is more general than Copy, you can automatically make anything Copy be Clone as well.

Derivable

This trait can be used with #[derive] if all fields are Clone. The derived implementation of clone calls clone on each field.

For a generic struct, #[derive] implements Clone conditionally by adding bound Clone on generic parameters.

// `derive` implements Clone for Reading<T> when T is Clone.
#[derive(Clone)]
struct Reading<T> {
    frequency: T,
}Run

How can I implement `Clone`?

Types that are Copy should have a trivial implementation of Clone. More formally: if T: Copy, x: T, and y: &T, then let x = y.clone(); is equivalent to let x = *y;. Manual implementations should be careful to uphold this invariant; however, unsafe code must not rely on it to ensure memory safety.

An example is a generic struct holding a function pointer. In this case, the implementation of Clone cannot be derived, but can be implemented as:

struct Generate<T>(fn() -> T);

impl<T> Copy for Generate<T> {}

impl<T> Clone for Generate<T> {
    fn clone(&self) -> Self {
        *self
    }
}Run

Additional implementors

In addition to the implementors listed below, the following types also implement Clone:

Function item types (i.e., the distinct types defined for each function)
Function pointer types (e.g., fn() -> i32)
Array types, for all sizes, if the item type also implements Clone (e.g., [i32; 123456])
Tuple types, if each component also implements Clone (e.g., (), (i32, bool))
Closure types, if they capture no value from the environment or if all such captured values implement Clone themselves. Note that variables captured by shared reference always implement Clone (even if the referent doesn't), while variables captured by mutable reference never implement Clone.

Required methods

`[+] Expand attributes #[must_use = "cloning is often expensive and is not expected to have side effects"] fn clone(&self) -> Self`[−]

Returns a copy of the value.

Examples

let hello = "Hello"; // &str implements Clone

assert_eq!("Hello", hello.clone());Run

Provided methods

`fn clone_from(&mut self, source: &Self)`[−]

Performs copy-assignment from source.

a.clone_from(&b) is equivalent to a = b.clone() in functionality, but can be overridden to reuse the resources of a to avoid unnecessary allocations.

1.0.0[−][src]Trait core::clone::Clone

Derivable

How can I implement Clone?

Additional implementors

Required methods

[+] Expand attributes#[must_use = "cloning is often expensive and is not expected to have side effects"] fn clone(&self) -> Self[−]

Examples

Provided methods

fn clone_from(&mut self, source: &Self)[−]

Implementors

impl Clone for ![src][−]

fn clone(&self) -> Self[src]

impl Clone for core::cmp::Ordering[src][−]

fn clone(&self) -> Ordering[src]

impl Clone for Infallible[src][−]

fn clone(&self) -> Infallible[src]

impl Clone for FpCategory[src][−]

fn clone(&self) -> FpCategory[src]

impl Clone for IntErrorKind[src][−]

fn clone(&self) -> IntErrorKind[src]

impl Clone for SearchStep[src][−]

fn clone(&self) -> SearchStep[src]

impl Clone for core::sync::atomic::Ordering[src][−]

fn clone(&self) -> Ordering[src]

impl Clone for AllocErr[src][−]

fn clone(&self) -> AllocErr[src]

impl Clone for CannotReallocInPlace[src][−]

fn clone(&self) -> CannotReallocInPlace[src]

impl Clone for Layout[src][−]

fn clone(&self) -> Layout[src]

impl Clone for LayoutErr[src][−]

fn clone(&self) -> LayoutErr[src]

impl Clone for TypeId[src][−]

fn clone(&self) -> TypeId[src]

impl Clone for float64x1_t[src][−]

fn clone(&self) -> float64x1_t[src]

impl Clone for float64x2_t[src][−]

fn clone(&self) -> float64x2_t[src]

impl Clone for int8x16x2_t[src][−]

fn clone(&self) -> int8x16x2_t[src]

impl Clone for int8x16x3_t[src][−]

fn clone(&self) -> int8x16x3_t[src]

impl Clone for int8x16x4_t[src][−]

fn clone(&self) -> int8x16x4_t[src]

impl Clone for poly64x1_t[src][−]

fn clone(&self) -> poly64x1_t[src]

impl Clone for poly64x2_t[src][−]

fn clone(&self) -> poly64x2_t[src]

impl Clone for poly8x16x2_t[src][−]

fn clone(&self) -> poly8x16x2_t[src]

impl Clone for poly8x16x3_t[src][−]

fn clone(&self) -> poly8x16x3_t[src]

impl Clone for poly8x16x4_t[src][−]

fn clone(&self) -> poly8x16x4_t[src]

impl Clone for uint8x16x2_t[src][−]

fn clone(&self) -> uint8x16x2_t[src]

impl Clone for uint8x16x3_t[src][−]

fn clone(&self) -> uint8x16x3_t[src]

impl Clone for uint8x16x4_t[src][−]

fn clone(&self) -> uint8x16x4_t[src]

impl Clone for float32x2_t[src][−]

fn clone(&self) -> float32x2_t[src]

impl Clone for float32x4_t[src][−]

fn clone(&self) -> float32x4_t[src]

impl Clone for int16x4_t[src][−]

fn clone(&self) -> int16x4_t[src]

impl Clone for int16x8_t[src][−]

fn clone(&self) -> int16x8_t[src]

impl Clone for int32x2_t[src][−]

fn clone(&self) -> int32x2_t[src]

impl Clone for int32x4_t[src][−]

fn clone(&self) -> int32x4_t[src]

impl Clone for int64x1_t[src][−]

fn clone(&self) -> int64x1_t[src]

impl Clone for int64x2_t[src][−]

fn clone(&self) -> int64x2_t[src]

impl Clone for int8x16_t[src][−]

fn clone(&self) -> int8x16_t[src]

impl Clone for int8x8_t[src][−]

fn clone(&self) -> int8x8_t[src]

How can I implement `Clone`?

`[+] Expand attributes #[must_use = "cloning is often expensive and is not expected to have side effects"] fn clone(&self) -> Self`[−]

`fn clone_from(&mut self, source: &Self)`[−]

`impl Clone for !`[src][−]

`fn clone(&self) -> Self`[src]

`impl Clone for core::cmp::Ordering`[src][−]

`fn clone(&self) -> Ordering`[src]

`impl Clone for Infallible`[src][−]

`fn clone(&self) -> Infallible`[src]

`impl Clone for FpCategory`[src][−]

`fn clone(&self) -> FpCategory`[src]

`impl Clone for IntErrorKind`[src][−]

`fn clone(&self) -> IntErrorKind`[src]

`impl Clone for SearchStep`[src][−]

`fn clone(&self) -> SearchStep`[src]

`impl Clone for core::sync::atomic::Ordering`[src][−]

`fn clone(&self) -> Ordering`[src]

`impl Clone for AllocErr`[src][−]

`fn clone(&self) -> AllocErr`[src]

`impl Clone for CannotReallocInPlace`[src][−]

`fn clone(&self) -> CannotReallocInPlace`[src]

`impl Clone for Layout`[src][−]

`fn clone(&self) -> Layout`[src]

`impl Clone for LayoutErr`[src][−]

`fn clone(&self) -> LayoutErr`[src]

`impl Clone for TypeId`[src][−]

`fn clone(&self) -> TypeId`[src]

`impl Clone for float64x1_t`[src][−]

`fn clone(&self) -> float64x1_t`[src]

`impl Clone for float64x2_t`[src][−]

`fn clone(&self) -> float64x2_t`[src]

`impl Clone for int8x16x2_t`[src][−]

`fn clone(&self) -> int8x16x2_t`[src]

`impl Clone for int8x16x3_t`[src][−]

`fn clone(&self) -> int8x16x3_t`[src]

`impl Clone for int8x16x4_t`[src][−]

`fn clone(&self) -> int8x16x4_t`[src]

`impl Clone for poly64x1_t`[src][−]

`fn clone(&self) -> poly64x1_t`[src]

`impl Clone for poly64x2_t`[src][−]

`fn clone(&self) -> poly64x2_t`[src]

`impl Clone for poly8x16x2_t`[src][−]

`fn clone(&self) -> poly8x16x2_t`[src]

`impl Clone for poly8x16x3_t`[src][−]

`fn clone(&self) -> poly8x16x3_t`[src]

`impl Clone for poly8x16x4_t`[src][−]

`fn clone(&self) -> poly8x16x4_t`[src]

`impl Clone for uint8x16x2_t`[src][−]

`fn clone(&self) -> uint8x16x2_t`[src]

`impl Clone for uint8x16x3_t`[src][−]

`fn clone(&self) -> uint8x16x3_t`[src]

`impl Clone for uint8x16x4_t`[src][−]

`fn clone(&self) -> uint8x16x4_t`[src]

`impl Clone for float32x2_t`[src][−]

`fn clone(&self) -> float32x2_t`[src]

`impl Clone for float32x4_t`[src][−]

`fn clone(&self) -> float32x4_t`[src]

`impl Clone for int16x4_t`[src][−]

`fn clone(&self) -> int16x4_t`[src]

`impl Clone for int16x8_t`[src][−]

`fn clone(&self) -> int16x8_t`[src]

`impl Clone for int32x2_t`[src][−]

`fn clone(&self) -> int32x2_t`[src]

`impl Clone for int32x4_t`[src][−]

`fn clone(&self) -> int32x4_t`[src]

`impl Clone for int64x1_t`[src][−]

`fn clone(&self) -> int64x1_t`[src]

`impl Clone for int64x2_t`[src][−]

`fn clone(&self) -> int64x2_t`[src]

`impl Clone for int8x16_t`[src][−]

`fn clone(&self) -> int8x16_t`[src]

`impl Clone for int8x8_t`[src][−]

`fn clone(&self) -> int8x8_t`[src]

`impl Clone for int8x8x2_t`[src][−]

`fn clone(&self) -> int8x8x2_t`[src]

`impl Clone for int8x8x3_t`[src][−]

`fn clone(&self) -> int8x8x3_t`[src]

`impl Clone for int8x8x4_t`[src][−]

`fn clone(&self) -> int8x8x4_t`[src]

`impl Clone for poly16x4_t`[src][−]