core::clone::Clone - Rust
Description: API documentation for the Rust `Clone` trait in crate `core`.
Keywords: rust, rustlang, rust-lang, Clone

# Trait core::clone::Clone 1.0.0[−][src]

    #[lang = "clone"]
    pub trait Clone: Sized {
        #[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 `derive`d implementation of `clone` calls `clone` on each field.

## 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 an array holding more than 32 elements of a type that is `Clone`; the standard library only implements `Clone` up until arrays of size 32. In this case, the implementation of `Clone` cannot be `derive`d, but can be implemented as:

    #[derive(Copy)]
    struct Stats {
       frequencies: [i32; 100],
    }

    impl Clone for Stats {
        fn clone(&self) -> Stats { *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

### `
#[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.

## Implementors

- `impl Clone for ParseFloatError` | [src]

- `impl Clone for NonZeroU8` | [src]

- `impl Clone for NonZeroU16` | [src]

- `impl Clone for NonZeroU32` | [src]

- `impl Clone for NonZeroU64` | [src]

- `impl Clone for NonZeroU128` | [src]

- `impl Clone for NonZeroUsize` | [src]

- `impl<T: Clone> Clone for Wrapping<T>` | [src]

- `impl Clone for FpCategory` | [src]

- `impl Clone for TryFromIntError` | [src]

- `impl Clone for ParseIntError` | [src]

- `impl<T> Clone for Discriminant<T>` | [src]

- `impl<T: Clone> Clone for ManuallyDrop<T>` | [src]

- `impl<T: ?Sized> Clone for NonNull<T>` | [src]

- `impl<T: ?Sized> Clone for PhantomData<T>` | [src]

- `impl Clone for Pinned` | [src]

- `impl<Y: Clone, R: Clone> Clone for GeneratorState<Y, R>` | [src]

- `impl Clone for RangeFull` | [src]

- `impl<Idx: Clone> Clone for Range<Idx>` | [src]

- `impl<Idx: Clone> Clone for RangeFrom<Idx>` | [src]

- `impl<Idx: Clone> Clone for RangeTo<Idx>` | [src]

- `impl<Idx: Clone> Clone for RangeInclusive<Idx>` | [src]

- `impl<Idx: Clone> Clone for RangeToInclusive<Idx>` | [src]

- `impl<T: Clone> Clone for Bound<T>` | [src]

- `impl Clone for core::cmp::Ordering` | [src]

- `impl<T: Clone> Clone for Reverse<T>` | [src]

- `impl Clone for usize` | [src]

- `impl Clone for u8` | [src]

- `impl Clone for u16` | [src]

- `impl Clone for u32` | [src]

- `impl Clone for u64` | [src]

- `impl Clone for u128` | [src]

- `impl Clone for isize` | [src]

- `impl Clone for i8` | [src]

- `impl Clone for i16` | [src]

- `impl Clone for i32` | [src]

- `impl Clone for i64` | [src]

- `impl Clone for i128` | [src]

- `impl Clone for f32` | [src]

- `impl Clone for f64` | [src]

- `impl Clone for bool` | [src]

- `impl Clone for char` | [src]

- `impl Clone for !` | [src]

- `impl<T: ?Sized> Clone for *const T` | [src]

- `impl<T: ?Sized> Clone for *mut T` | [src]

- `impl<'a, T: ?Sized> Clone for &'a T` | [src]

- `impl Clone for TypeId` | [src]

- `impl Clone for TryFromSliceError` | [src]

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

- `impl<T: Copy> Clone for Cell<T>` | [src]

- `impl<T: Clone> Clone for RefCell<T>` | [src]

- `impl Clone for ParseCharError` | [src]

- `impl Clone for CharTryFromError` | [src]

- `impl<I: Clone + Iterator<Item = u8>> Clone for DecodeUtf8<I>` | [src]

- `impl<I: Clone> Clone for DecodeUtf16<I> where I: Iterator<Item = u16>,` | [src]

- `impl Clone for DecodeUtf16Error` | [src]

- `impl Clone for EscapeUnicode` | [src]

- `impl Clone for EscapeDefault` | [src]

- `impl Clone for EscapeDebug` | [src]

- `impl Clone for ToLowercase` | [src]

- `impl Clone for ToUppercase` | [src]

- `impl<A: Clone> Clone for Repeat<A>` | [src]

- `impl<F: Clone> Clone for RepeatWith<F>` | [src]

- `impl<T> Clone for Empty<T>` | [src]

- `impl<T: Clone> Clone for Once<T>` | [src]

- `impl<T: Clone> Clone for Rev<T>` | [src]

- `impl<I: Clone> Clone for Cloned<I>` | [src]

- `impl<I: Clone> Clone for Cycle<I>` | [src]

- `impl<I: Clone> Clone for StepBy<I>` | [src]

- `impl<A: Clone, B: Clone> Clone for Chain<A, B>` | [src]

- `impl<A: Clone, B: Clone> Clone for Zip<A, B>` | [src]

- `impl<I: Clone, F: Clone> Clone for Map<I, F>` | [src]

- `impl<I: Clone, P: Clone> Clone for Filter<I, P>` | [src]

- `impl<I: Clone, F: Clone> Clone for FilterMap<I, F>` | [src]

- `impl<I: Clone> Clone for Enumerate<I>` | [src]

- `impl<I: Clone + Iterator> Clone for Peekable<I> where I::Item: Clone,` | [src]

- `impl<I: Clone, P: Clone> Clone for SkipWhile<I, P>` | [src]

- `impl<I: Clone, P: Clone> Clone for TakeWhile<I, P>` | [src]

- `impl<I: Clone> Clone for Skip<I>` | [src]

- `impl<I: Clone> Clone for Take<I>` | [src]

- `impl<I: Clone, St: Clone, F: Clone> Clone for Scan<I, St, F>` | [src]

- `impl<I: Clone, U: Clone + IntoIterator, F: Clone> Clone for FlatMap<I, U, F> where <U as IntoIterator>::IntoIter: Clone,` | [src]

- `impl<I, U> Clone for Flatten<I> where I: Iterator + Clone, U: Iterator + Clone, I::Item: IntoIterator<IntoIter = U, Item = U::Item>,` | [src]

- `impl<I: Clone> Clone for Fuse<I>` | [src]

- `impl<I: Clone, F: Clone> Clone for Inspect<I, F>` | [src]

- `impl<T: Clone> Clone for Option<T>` | [src]

- `impl<'a, A> Clone for core::option::Iter<'a, A>` | [src]

- `impl<A: Clone> Clone for core::option::IntoIter<A>` | [src]

- `impl Clone for NoneError` | [src]

- `impl Clone for TraitObject` | [src]

- `impl<T: Clone, E: Clone> Clone for Result<T, E>` | [src]

- `impl<'a, T> Clone for core::result::Iter<'a, T>` | [src]

- `impl<T: Clone> Clone for core::result::IntoIter<T>` | [src]

- `impl<'a, T> Clone for core::slice::Iter<'a, T>` | [src]

- `impl<'a, T, P> Clone for core::slice::Split<'a, T, P> where P: Clone + FnMut(&T) -> bool,` | [src]

- `impl<'a, T: Clone + 'a, P: Clone> Clone for core::slice::RSplit<'a, T, P> where P: FnMut(&T) -> bool,` | [src]

- `impl<'a, T> Clone for Windows<'a, T>` | [src]

- `impl<'a, T> Clone for Chunks<'a, T>` | [src]

- `impl<'a, T> Clone for ExactChunks<'a, T>` | [src]

- `impl Clone for SearchStep` | [src]

- `impl<'a> Clone for CharSearcher<'a>` | [src]

- `impl<'a, 'b> Clone for CharSliceSearcher<'a, 'b>` | [src]

- `impl<'a, F: Clone> Clone for CharPredicateSearcher<'a, F> where F: FnMut(char) -> bool,` | [src]

- `impl<'a, 'b> Clone for StrSearcher<'a, 'b>` | [src]

- `impl Clone for ParseBoolError` | [src]

- `impl Clone for Utf8Error` | [src]

- `impl<'a> Clone for Chars<'a>` | [src]

- `impl<'a> Clone for CharIndices<'a>` | [src]

- `impl<'a> Clone for Bytes<'a>` | [src]

- `impl<'a, P: Pattern<'a>> Clone for core::str::Split<'a, P> where P::Searcher: Clone,` | [src]

- `impl<'a, P: Pattern<'a>> Clone for core::str::RSplit<'a, P> where P::Searcher: Clone,` | [src]

- `impl<'a, P: Pattern<'a>> Clone for SplitTerminator<'a, P> where P::Searcher: Clone,` | [src]

- `impl<'a, P: Pattern<'a>> Clone for RSplitTerminator<'a, P> where P::Searcher: Clone,` | [src]

- `impl<'a, P: Pattern<'a>> Clone for SplitN<'a, P> where P::Searcher: Clone,` | [src]

- `impl<'a, P: Pattern<'a>> Clone for RSplitN<'a, P> where P::Searcher: Clone,` | [src]

- `impl<'a, P: Pattern<'a>> Clone for MatchIndices<'a, P> where P::Searcher: Clone,` | [src]

- `impl<'a, P: Pattern<'a>> Clone for RMatchIndices<'a, P> where P::Searcher: Clone,` | [src]

- `impl<'a, P: Pattern<'a>> Clone for Matches<'a, P> where P::Searcher: Clone,` | [src]

- `impl<'a, P: Pattern<'a>> Clone for RMatches<'a, P> where P::Searcher: Clone,` | [src]

- `impl<'a> Clone for Lines<'a>` | [src]

- `impl<'a> Clone for LinesAny<'a>` | [src]

- `impl<'a> Clone for SplitWhitespace<'a>` | [src]

- `impl<'a> Clone for SplitAsciiWhitespace<'a>` | [src]

- `impl<'a> Clone for EncodeUtf16<'a>` | [src]

- `impl Clone for SipHasher` | [src]

- `impl<H> Clone for BuildHasherDefault<H>` | [src]

- `impl Clone for Error` | [src]

- `impl<'a> Clone for Arguments<'a>` | [src]

- `impl Clone for Duration` | [src]

- `impl Clone for UnicodeVersion` | [src]

- `impl<T: Clone> Clone for Poll<T>` | [src]

- `impl Clone for Waker` | [src]

- `impl Clone for LocalWaker` | [src]

- `impl Clone for Layout` | [src]

- `impl Clone for LayoutErr` | [src]

- `impl Clone for AllocErr` | [src]

- `impl Clone for CannotReallocInPlace` | [src]

- `impl Clone for CpuidResult` | [src]

- `impl Clone for __m64` | [src]

- `impl Clone for __m128i` | [src]

- `impl Clone for __m128` | [src]

- `impl Clone for __m128d` | [src]

- `impl Clone for __m256i` | [src]

- `impl Clone for __m256` | [src]

- `impl Clone for __m256d` | [src]

- `impl Clone for float64x1_t` | [src]

- `impl Clone for float64x2_t` | [src]

- `impl Clone for int8x4_t` | [src]

- `impl Clone for uint8x4_t` | [src]

- `impl Clone for int16x2_t` | [src]

- `impl Clone for uint16x2_t` | [src]

- `impl Clone for int8x8_t` | [src]

- `impl Clone for uint8x8_t` | [src]

- `impl Clone for poly8x8_t` | [src]

- `impl Clone for int16x4_t` | [src]

- `impl Clone for uint16x4_t` | [src]

- `impl Clone for poly16x4_t` | [src]

- `impl Clone for int32x2_t` | [src]

- `impl Clone for uint32x2_t` | [src]

- `impl Clone for float32x2_t` | [src]

- `impl Clone for int64x1_t` | [src]

- `impl Clone for uint64x1_t` | [src]

- `impl Clone for int8x16_t` | [src]

- `impl Clone for uint8x16_t` | [src]

- `impl Clone for poly8x16_t` | [src]

- `impl Clone for int16x8_t` | [src]

- `impl Clone for uint16x8_t` | [src]

- `impl Clone for poly16x8_t` | [src]

- `impl Clone for int32x4_t` | [src]

- `impl Clone for uint32x4_t` | [src]

- `impl Clone for float32x4_t` | [src]

- `impl Clone for int64x2_t` | [src]

- `impl Clone for uint64x2_t` | [src]

- `impl Clone for i8x16` | [src]

- `impl Clone for vector_signed_long` | [src]

- `impl Clone for vector_unsigned_long` | [src]

- `impl Clone for vector_bool_long` | [src]

- `impl Clone for vector_double` | [src]

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