pub trait Clone: Sized {
// Required method
fn clone(&self) -> Self;
// Provided method
fn clone_from(&mut self, source: &Self) { ... }
}
Expand description
A common trait for the ability to explicitly duplicate an object.
Differs from Copy
in that Copy
is implicit and an inexpensive bit-wise copy, 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.
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,
}
§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 derive
d, 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
}
}
If we derive
:
the auto-derived implementations will have unnecessary T: Copy
and T: Clone
bounds:
// Automatically derived
impl<T: Copy> Copy for Generate<T> { }
// Automatically derived
impl<T: Clone> Clone for Generate<T> {
fn clone(&self) -> Generate<T> {
Generate(Clone::clone(&self.0))
}
}
The bounds are unnecessary because clearly the function itself should be copy- and cloneable even if its return type is not:
#[derive(Copy, Clone)]
struct Generate<T>(fn() -> T);
struct NotCloneable;
fn generate_not_cloneable() -> NotCloneable {
NotCloneable
}
Generate(generate_not_cloneable).clone(); // error: trait bounds were not satisfied
// Note: With the manual implementations the above line will compile.
§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
) - 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 implementClone
(even if the referent doesn’t), while variables captured by mutable reference never implementClone
.
Required Methods§
Provided Methods§
1.0.0 · Sourcefn clone_from(&mut self, source: &Self)
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.
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.
Implementors§
impl Clone for AsciiChar
impl Clone for core::cmp::Ordering
impl Clone for Infallible
impl Clone for core::fmt::Alignment
impl Clone for DebugAsHex
impl Clone for Sign
impl Clone for IpAddr
impl Clone for Ipv6MulticastScope
impl Clone for SocketAddr
impl Clone for FpCategory
impl Clone for IntErrorKind
impl Clone for SearchStep
impl Clone for core::sync::atomic::Ordering
impl Clone for bool
impl Clone for char
impl Clone for f16
impl Clone for f32
impl Clone for f64
impl Clone for f128
impl Clone for i8
impl Clone for i16
impl Clone for i32
impl Clone for i64
impl Clone for i128
impl Clone for isize
impl Clone for !
impl Clone for u8
impl Clone for u16
impl Clone for u32
impl Clone for u64
impl Clone for u128
impl Clone for usize
impl Clone for AllocError
impl Clone for Layout
impl Clone for LayoutError
impl Clone for TypeId
impl Clone for float64x1_t
target_arch="arm64ec"
only.impl Clone for float64x1x2_t
target_arch="arm64ec"
only.impl Clone for float64x1x3_t
target_arch="arm64ec"
only.impl Clone for float64x1x4_t
target_arch="arm64ec"
only.impl Clone for float64x2_t
target_arch="arm64ec"
only.impl Clone for float64x2x2_t
target_arch="arm64ec"
only.impl Clone for float64x2x3_t
target_arch="arm64ec"
only.impl Clone for float64x2x4_t
target_arch="arm64ec"
only.impl Clone for float32x2_t
impl Clone for float32x2x2_t
impl Clone for float32x2x3_t
impl Clone for float32x2x4_t
impl Clone for float32x4_t
impl Clone for float32x4x2_t
impl Clone for float32x4x3_t
impl Clone for float32x4x4_t
impl Clone for int8x4_t
impl Clone for int8x8_t
impl Clone for int8x8x2_t
impl Clone for int8x8x3_t
impl Clone for int8x8x4_t
impl Clone for int8x16_t
impl Clone for int8x16x2_t
impl Clone for int8x16x3_t
impl Clone for int8x16x4_t
impl Clone for int16x2_t
impl Clone for int16x4_t
impl Clone for int16x4x2_t
impl Clone for int16x4x3_t
impl Clone for int16x4x4_t
impl Clone for int16x8_t
impl Clone for int16x8x2_t
impl Clone for int16x8x3_t
impl Clone for int16x8x4_t
impl Clone for int32x2_t
impl Clone for int32x2x2_t
impl Clone for int32x2x3_t
impl Clone for int32x2x4_t
impl Clone for int32x4_t
impl Clone for int32x4x2_t
impl Clone for int32x4x3_t
impl Clone for int32x4x4_t
impl Clone for int64x1_t
impl Clone for int64x1x2_t
impl Clone for int64x1x3_t
impl Clone for int64x1x4_t
impl Clone for int64x2_t
impl Clone for int64x2x2_t
impl Clone for int64x2x3_t
impl Clone for int64x2x4_t
impl Clone for poly8x8_t
impl Clone for poly8x8x2_t
impl Clone for poly8x8x3_t
impl Clone for poly8x8x4_t
impl Clone for poly8x16_t
impl Clone for poly8x16x2_t
impl Clone for poly8x16x3_t
impl Clone for poly8x16x4_t
impl Clone for poly16x4_t
impl Clone for poly16x4x2_t
impl Clone for poly16x4x3_t
impl Clone for poly16x4x4_t
impl Clone for poly16x8_t
impl Clone for poly16x8x2_t
impl Clone for poly16x8x3_t
impl Clone for poly16x8x4_t
impl Clone for poly64x1_t
impl Clone for poly64x1x2_t
impl Clone for poly64x1x3_t
impl Clone for poly64x1x4_t
impl Clone for poly64x2_t
impl Clone for poly64x2x2_t
impl Clone for poly64x2x3_t
impl Clone for poly64x2x4_t
impl Clone for uint8x4_t
impl Clone for uint8x8_t
impl Clone for uint8x8x2_t
impl Clone for uint8x8x3_t
impl Clone for uint8x8x4_t
impl Clone for uint8x16_t
impl Clone for uint8x16x2_t
impl Clone for uint8x16x3_t
impl Clone for uint8x16x4_t
impl Clone for uint16x2_t
impl Clone for uint16x4_t
impl Clone for uint16x4x2_t
impl Clone for uint16x4x3_t
impl Clone for uint16x4x4_t
impl Clone for uint16x8_t
impl Clone for uint16x8x2_t
impl Clone for uint16x8x3_t
impl Clone for uint16x8x4_t
impl Clone for uint32x2_t
impl Clone for uint32x2x2_t
impl Clone for uint32x2x3_t
impl Clone for uint32x2x4_t
impl Clone for uint32x4_t
impl Clone for uint32x4x2_t
impl Clone for uint32x4x3_t
impl Clone for uint32x4x4_t
impl Clone for uint64x1_t
impl Clone for uint64x1x2_t
impl Clone for uint64x1x3_t
impl Clone for uint64x1x4_t
impl Clone for uint64x2_t
impl Clone for uint64x2x2_t
impl Clone for uint64x2x3_t
impl Clone for uint64x2x4_t
impl Clone for v2f64
impl Clone for v2i64
impl Clone for v2u64
impl Clone for v4f32
impl Clone for v4f64
impl Clone for v4i32
impl Clone for v4i64
impl Clone for v4u32
impl Clone for v4u64
impl Clone for v8f32
impl Clone for v8i16
impl Clone for v8i32
impl Clone for v8u16
impl Clone for v8u32
impl Clone for v16i8
impl Clone for v16i16
impl Clone for v16u8
impl Clone for v16u16
impl Clone for v32i8
impl Clone for v32u8
impl Clone for f16x2
target_arch="nvptx64"
only.impl Clone for vector_bool_char
impl Clone for vector_bool_int
impl Clone for vector_bool_long
impl Clone for vector_bool_short
impl Clone for vector_double
impl Clone for vector_float
impl Clone for vector_signed_char
impl Clone for vector_signed_int
impl Clone for vector_signed_long
impl Clone for vector_signed_short
impl Clone for vector_unsigned_char
impl Clone for vector_unsigned_int
impl Clone for vector_unsigned_long
impl Clone for vector_unsigned_short
impl Clone for v128
target_family="wasm"
only.impl Clone for CpuidResult
impl Clone for __m128
impl Clone for __m128bh
impl Clone for __m128d
impl Clone for __m128h
impl Clone for __m128i
impl Clone for __m256
impl Clone for __m256bh
impl Clone for __m256d
impl Clone for __m256h
impl Clone for __m256i
impl Clone for __m512
impl Clone for __m512bh
impl Clone for __m512d
impl Clone for __m512h
impl Clone for __m512i
impl Clone for bf16
impl Clone for TryFromSliceError
impl Clone for core::ascii::EscapeDefault
impl Clone for CharTryFromError
impl Clone for DecodeUtf16Error
impl Clone for core::char::EscapeDebug
impl Clone for core::char::EscapeDefault
impl Clone for core::char::EscapeUnicode
impl Clone for ParseCharError
impl Clone for ToLowercase
impl Clone for ToUppercase
impl Clone for TryFromCharError
impl Clone for FromBytesUntilNulError
impl Clone for FromBytesWithNulError
impl Clone for Error
impl Clone for FormattingOptions
impl Clone for SipHasher
impl Clone for PhantomPinned
impl Clone for Assume
impl Clone for AddrParseError
impl Clone for Ipv4Addr
impl Clone for Ipv6Addr
impl Clone for SocketAddrV4
impl Clone for SocketAddrV6
impl Clone for ParseFloatError
impl Clone for ParseIntError
impl Clone for TryFromIntError
impl Clone for RangeFull
impl Clone for core::ptr::Alignment
impl Clone for ParseBoolError
impl Clone for Utf8Error
impl Clone for LocalWaker
impl Clone for RawWakerVTable
impl Clone for Waker
impl Clone for Duration
impl Clone for TryFromFloatSecsError
impl<'a> Clone for Utf8Pattern<'a>
impl<'a> Clone for Source<'a>
impl<'a> Clone for core::ffi::c_str::Bytes<'a>
impl<'a> Clone for Arguments<'a>
impl<'a> Clone for Location<'a>
impl<'a> Clone for EscapeAscii<'a>
impl<'a> Clone for CharSearcher<'a>
impl<'a> Clone for core::str::Bytes<'a>
impl<'a> Clone for CharIndices<'a>
impl<'a> Clone for Chars<'a>
impl<'a> Clone for EncodeUtf16<'a>
impl<'a> Clone for core::str::EscapeDebug<'a>
impl<'a> Clone for core::str::EscapeDefault<'a>
impl<'a> Clone for core::str::EscapeUnicode<'a>
impl<'a> Clone for Lines<'a>
impl<'a> Clone for LinesAny<'a>
impl<'a> Clone for SplitAsciiWhitespace<'a>
impl<'a> Clone for SplitWhitespace<'a>
impl<'a> Clone for Utf8Chunk<'a>
impl<'a> Clone for Utf8Chunks<'a>
impl<'a, 'b> Clone for CharSliceSearcher<'a, 'b>
impl<'a, 'b> Clone for StrSearcher<'a, 'b>
impl<'a, 'b, const N: usize> Clone for CharArrayRefSearcher<'a, 'b, N>
impl<'a, F> Clone for CharPredicateSearcher<'a, F>
impl<'a, P> Clone for MatchIndices<'a, P>
impl<'a, P> Clone for Matches<'a, P>
impl<'a, P> Clone for RMatchIndices<'a, P>
impl<'a, P> Clone for RMatches<'a, P>
impl<'a, P> Clone for core::str::RSplit<'a, P>
impl<'a, P> Clone for RSplitN<'a, P>
impl<'a, P> Clone for RSplitTerminator<'a, P>
impl<'a, P> Clone for core::str::Split<'a, P>
impl<'a, P> Clone for SplitN<'a, P>
impl<'a, P> Clone for SplitTerminator<'a, P>
impl<'a, P: Pattern<Searcher<'a>: Clone>> Clone for core::str::SplitInclusive<'a, P>
impl<'a, T> Clone for RChunksExact<'a, T>
impl<'a, T: Clone + 'a, const N: usize> Clone for ArrayWindows<'a, T, N>
impl<'a, const N: usize> Clone for CharArraySearcher<'a, N>
impl<'f> Clone for VaListImpl<'f>
impl<A> Clone for core::option::Iter<'_, A>
impl<A: Clone> Clone for Repeat<A>
impl<A: Clone> Clone for RepeatN<A>
impl<A: Clone> Clone for core::option::IntoIter<A>
impl<A: Clone> Clone for IterRange<A>
impl<A: Clone> Clone for IterRangeFrom<A>
impl<A: Clone> Clone for IterRangeInclusive<A>
impl<A: Clone, B: Clone> Clone for Chain<A, B>
impl<A: Clone, B: Clone> Clone for Zip<A, B>
impl<B: Clone, C: Clone> Clone for ControlFlow<B, C>
impl<Dyn: ?Sized> Clone for DynMetadata<Dyn>
impl<F: Clone> Clone for FromFn<F>
impl<F: Clone> Clone for OnceWith<F>
impl<F: Clone> Clone for RepeatWith<F>
impl<H> Clone for BuildHasherDefault<H>
impl<I> Clone for DecodeUtf16<I>
impl<I, F, const N: usize> Clone for MapWindows<I, F, N>
impl<I, G> Clone for IntersperseWith<I, G>
impl<I, U> Clone for Flatten<I>
impl<I: Clone + Iterator> Clone for Intersperse<I>
impl<I: Clone + Iterator> Clone for Peekable<I>
impl<I: Clone + Iterator, const N: usize> Clone for core::iter::ArrayChunks<I, N>
impl<I: Clone> Clone for FromIter<I>
impl<I: Clone> Clone for Cloned<I>
impl<I: Clone> Clone for Copied<I>
impl<I: Clone> Clone for Cycle<I>
impl<I: Clone> Clone for Enumerate<I>
impl<I: Clone> Clone for Fuse<I>
impl<I: Clone> Clone for Skip<I>
impl<I: Clone> Clone for StepBy<I>
impl<I: Clone> Clone for Take<I>
impl<I: Clone, F: Clone> Clone for FilterMap<I, F>
impl<I: Clone, F: Clone> Clone for Inspect<I, F>
impl<I: Clone, F: Clone> Clone for Map<I, F>
impl<I: Clone, P: Clone> Clone for Filter<I, P>
impl<I: Clone, P: Clone> Clone for MapWhile<I, P>
impl<I: Clone, P: Clone> Clone for SkipWhile<I, P>
impl<I: Clone, P: Clone> Clone for TakeWhile<I, P>
impl<I: Clone, St: Clone, F: Clone> Clone for Scan<I, St, F>
impl<I: Clone, U, F: Clone> Clone for FlatMap<I, U, F>
impl<Idx: Clone> Clone for core::ops::Range<Idx>
impl<Idx: Clone> Clone for core::ops::RangeFrom<Idx>
impl<Idx: Clone> Clone for core::ops::RangeInclusive<Idx>
impl<Idx: Clone> Clone for RangeTo<Idx>
impl<Idx: Clone> Clone for RangeToInclusive<Idx>
impl<Idx: Clone> Clone for core::range::Range<Idx>
impl<Idx: Clone> Clone for core::range::RangeFrom<Idx>
impl<Idx: Clone> Clone for core::range::RangeInclusive<Idx>
impl<Ptr: Clone> Clone for Pin<Ptr>
impl<T> Clone for Option<T>where
T: Clone,
impl<T> Clone for Pending<T>
impl<T> Clone for Empty<T>
impl<T> Clone for Discriminant<T>
impl<T> Clone for NonZero<T>where
T: ZeroablePrimitive,
impl<T> Clone for core::result::Iter<'_, T>
impl<T> Clone for Chunks<'_, T>
impl<T> Clone for ChunksExact<'_, T>
impl<T> Clone for core::slice::Iter<'_, T>
impl<T> Clone for RChunks<'_, T>
impl<T> Clone for Windows<'_, T>
impl<T, E> Clone for Result<T, E>
impl<T, P> Clone for core::slice::RSplit<'_, T, P>
impl<T, P> Clone for core::slice::Split<'_, T, P>
impl<T, P> Clone for core::slice::SplitInclusive<'_, T, P>
impl<T, const N: usize> Clone for Mask<T, N>
impl<T, const N: usize> Clone for Simd<T, N>
impl<T, const N: usize> Clone for core::slice::ArrayChunks<'_, T, N>
impl<T: Copy> Clone for Cell<T>
impl<T: Copy> Clone for MaybeUninit<T>
impl<T: Clone + ?Sized> Clone for ManuallyDrop<T>
impl<T: Clone> Clone for Bound<T>
impl<T: Clone> Clone for Poll<T>
impl<T: Clone> Clone for OnceCell<T>
impl<T: Clone> Clone for RefCell<T>
impl<T: Clone> Clone for Reverse<T>
impl<T: Clone> Clone for Ready<T>
impl<T: Clone> Clone for Once<T>
impl<T: Clone> Clone for Rev<T>
impl<T: Clone> Clone for Saturating<T>
impl<T: Clone> Clone for Wrapping<T>
impl<T: Clone> Clone for core::result::IntoIter<T>
impl<T: Clone, F: Clone> Clone for Successors<T, F>
impl<T: Clone, const N: usize> Clone for [T; N]
impl<T: Clone, const N: usize> Clone for core::array::IntoIter<T, N>
impl<T: ?Sized> !Clone for &mut T
Shared references can be cloned, but mutable references cannot!
impl<T: ?Sized> Clone for *const T
impl<T: ?Sized> Clone for *mut T
impl<T: ?Sized> Clone for &T
Shared references can be cloned, but mutable references cannot!