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
:
#[derive(Copy, Clone)]
struct Generate<T>(fn() -> T);
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.
Object Safety§
Implementors§
impl Clone for uefi_std::cmp::Ordering
impl Clone for Infallible
impl Clone for uefi_std::fmt::Alignment
impl Clone for SearchStep
impl Clone for TryReserveErrorKind
impl Clone for AsciiChar
impl Clone for IpAddr
impl Clone for Ipv6MulticastScope
impl Clone for SocketAddr
impl Clone for FpCategory
impl Clone for IntErrorKind
impl Clone for core::sync::atomic::Ordering
impl Clone for DevicePathAcpiType
impl Clone for DevicePathBbsType
impl Clone for DevicePathEndType
impl Clone for DevicePathHardwareType
impl Clone for DevicePathMediaType
impl Clone for DevicePathMessagingType
impl Clone for DevicePathType
impl Clone for GraphicsBltOp
impl Clone for GraphicsPixelFormat
impl Clone for GuidKind
impl Clone for IfrOpCode
impl Clone for IfrTypeKind
impl Clone for IfrTypeValueEnum
impl Clone for HiiPackageKind
impl Clone for SibtKind
impl Clone for MemoryType
impl Clone for ResetType
impl Clone for uefi::status::Error
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 TypeId
impl Clone for CpuidResult
impl Clone for __m128
impl Clone for __m128bh
impl Clone for __m128d
impl Clone for __m128i
impl Clone for __m256
impl Clone for __m256bh
impl Clone for __m256d
impl Clone for __m256i
impl Clone for __m512
impl Clone for __m512bh
impl Clone for __m512d
impl Clone for __m512i
impl Clone for TryFromSliceError
impl Clone for Box<str>
impl Clone for Box<CStr>
impl Clone for CharTryFromError
impl Clone for DecodeUtf16Error
impl Clone for uefi_std::char::EscapeDebug
impl Clone for uefi_std::char::EscapeDefault
impl Clone for uefi_std::char::EscapeUnicode
impl Clone for ParseCharError
impl Clone for ToLowercase
impl Clone for ToUppercase
impl Clone for TryFromCharError
impl Clone for uefi_std::fmt::Error
impl Clone for SipHasher
impl Clone for PhantomPinned
impl Clone for Assume
impl Clone for RangeFull
impl Clone for uefi_std::ptr::Alignment
impl Clone for ParseBoolError
impl Clone for Utf8Error
impl Clone for FromUtf8Error
impl Clone for String
impl Clone for Global
impl Clone for UnorderedKeyError
impl Clone for TryReserveError
impl Clone for CString
impl Clone for FromVecWithNulError
impl Clone for IntoStringError
impl Clone for NulError
impl Clone for Layout
impl Clone for LayoutError
impl Clone for AllocError
impl Clone for core::ascii::EscapeDefault
impl Clone for FromBytesUntilNulError
impl Clone for FromBytesWithNulError
impl Clone for Ipv4Addr
impl Clone for Ipv6Addr
impl Clone for AddrParseError
impl Clone for SocketAddrV4
impl Clone for SocketAddrV6
impl Clone for ParseFloatError
impl Clone for ParseIntError
impl Clone for TryFromIntError
impl Clone for TimSortRun
impl Clone for LocalWaker
impl Clone for RawWakerVTable
impl Clone for Waker
impl Clone for Duration
impl Clone for TryFromFloatSecsError
impl Clone for GraphicsBltPixel
impl Clone for GraphicsOutputModeInfo
impl Clone for GraphicsPixelBitmask
impl Clone for Guid
impl Clone for HiiHandle
impl Clone for HiiDate
impl Clone for HiiRef
impl Clone for HiiTime
impl Clone for IfrOpHeader
impl Clone for IfrQuestionHeader
impl Clone for IfrStatementHeader
impl Clone for AnimationId
impl Clone for FontStyle
impl Clone for FormId
impl Clone for ImageId
impl Clone for QuestionId
impl Clone for StringId
impl Clone for VarStoreId
impl Clone for MemoryDescriptor
impl Clone for PhysicalAddress
impl Clone for VirtualAddress
impl Clone for SimplePointerMode
impl Clone for SimplePointerState
impl Clone for Status
impl Clone for Event
impl Clone for Handle
impl Clone for Tpl
impl Clone for TextInputKey
impl Clone for TextOutputMode
impl Clone for Time
impl Clone for TimeCapabilities
impl Clone for IfrTypeValue
impl<'a> Clone for Arguments<'a>
impl<'a> Clone for EscapeAscii<'a>
impl<'a> Clone for CharSearcher<'a>
impl<'a> Clone for uefi_std::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 uefi_std::str::EscapeDebug<'a>
impl<'a> Clone for uefi_std::str::EscapeDefault<'a>
impl<'a> Clone for uefi_std::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> Clone for Source<'a>
impl<'a> Clone for core::ffi::c_str::Bytes<'a>
impl<'a> Clone for Location<'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 uefi_std::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 uefi_std::str::Split<'a, P>
impl<'a, P> Clone for uefi_std::str::SplitInclusive<'a, P>
impl<'a, P> Clone for SplitN<'a, P>
impl<'a, P> Clone for SplitTerminator<'a, P>
impl<'a, T> Clone for RChunksExact<'a, T>
impl<'a, T, const N: usize> Clone for ArrayWindows<'a, T, N>where
T: Clone + 'a,
impl<'a, const N: usize> Clone for CharArraySearcher<'a, N>
impl<'f> Clone for VaListImpl<'f>
impl<A> Clone for Repeat<A>where
A: Clone,
impl<A> Clone for RepeatN<A>where
A: Clone,
impl<A> Clone for uefi_std::option::IntoIter<A>where
A: Clone,
impl<A> Clone for uefi_std::option::Iter<'_, A>
impl<A, B> Clone for Chain<A, B>
impl<A, B> Clone for Zip<A, B>
impl<B> Clone for Cow<'_, B>
impl<B, C> Clone for ControlFlow<B, C>
impl<Dyn> Clone for DynMetadata<Dyn>where
Dyn: ?Sized,
impl<F> Clone for FromFn<F>where
F: Clone,
impl<F> Clone for OnceWith<F>where
F: Clone,
impl<F> Clone for RepeatWith<F>where
F: Clone,
impl<H> Clone for BuildHasherDefault<H>
impl<I> Clone for DecodeUtf16<I>
impl<I> Clone for Cloned<I>where
I: Clone,
impl<I> Clone for Copied<I>where
I: Clone,
impl<I> Clone for Cycle<I>where
I: Clone,
impl<I> Clone for Enumerate<I>where
I: Clone,
impl<I> Clone for Fuse<I>where
I: Clone,
impl<I> Clone for Intersperse<I>
impl<I> Clone for Peekable<I>
impl<I> Clone for Skip<I>where
I: Clone,
impl<I> Clone for StepBy<I>where
I: Clone,
impl<I> Clone for Take<I>where
I: Clone,
impl<I> Clone for FromIter<I>where
I: Clone,
impl<I, F> Clone for FilterMap<I, F>
impl<I, F> Clone for Inspect<I, F>
impl<I, F> Clone for Map<I, F>
impl<I, F, const N: usize> Clone for MapWindows<I, F, N>
impl<I, G> Clone for IntersperseWith<I, G>
impl<I, P> Clone for Filter<I, P>
impl<I, P> Clone for MapWhile<I, P>
impl<I, P> Clone for SkipWhile<I, P>
impl<I, P> Clone for TakeWhile<I, P>
impl<I, St, F> Clone for Scan<I, St, F>
impl<I, U> Clone for Flatten<I>
impl<I, U, F> Clone for FlatMap<I, U, F>
impl<I, const N: usize> Clone for uefi_std::iter::ArrayChunks<I, N>
impl<Idx> Clone for uefi_std::ops::Range<Idx>where
Idx: Clone,
impl<Idx> Clone for RangeFrom<Idx>where
Idx: Clone,
impl<Idx> Clone for RangeInclusive<Idx>where
Idx: Clone,
impl<Idx> Clone for RangeTo<Idx>where
Idx: Clone,
impl<Idx> Clone for RangeToInclusive<Idx>where
Idx: Clone,
impl<K, V> Clone for alloc::collections::btree::map::Cursor<'_, K, V>
impl<K, V> Clone for alloc::collections::btree::map::Iter<'_, K, V>
impl<K, V> Clone for Keys<'_, K, V>
impl<K, V> Clone for alloc::collections::btree::map::Range<'_, K, V>
impl<K, V> Clone for Values<'_, K, V>
impl<K, V, A> Clone for BTreeMap<K, V, A>
impl<Ptr> Clone for Pin<Ptr>where
Ptr: Clone,
impl<T> !Clone for &mut Twhere
T: ?Sized,
Shared references can be cloned, but mutable references cannot!
impl<T> Clone for Bound<T>where
T: Clone,
impl<T> Clone for Option<T>where
T: Clone,
impl<T> Clone for Poll<T>where
T: Clone,
impl<T> Clone for *const Twhere
T: ?Sized,
impl<T> Clone for *mut Twhere
T: ?Sized,
impl<T> Clone for &Twhere
T: ?Sized,
Shared references can be cloned, but mutable references cannot!