Trait std::clone::Clone1.0.0 [] [src]

#[lang = "clone"]
pub trait Clone { 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.

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 derived, but can be implemented as:

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

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

Required Methods

Returns a copy of the value.

Examples

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

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

Provided Methods

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.

Implementations on Foreign Types

impl Clone for Normal
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impl Clone for LogNormal
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impl Clone for ChaChaRng
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impl Clone for ReseedWithDefault
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impl Clone for XorShiftRng
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impl Clone for IsaacRng
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impl Clone for StandardNormal
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impl Clone for Exp1
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impl Clone for Exp
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impl Clone for Isaac64Rng
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impl Clone for _Unwind_Reason_Code

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impl Clone for _Unwind_Action

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impl<I> Clone for Utf16Encoder<I> where
    I: Clone
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impl<T> Clone for NonZero<T> where
    T: Zeroable + Clone
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impl Clone for fd_set
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impl Clone for sigset_t
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impl Clone for in6_addr
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impl Clone for epoll_event
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impl Clone for fsid_t
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impl Clone for ff_effect
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impl Clone for hostent
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impl Clone for dirent
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impl Clone for termios
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impl Clone for sockaddr_ll
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impl Clone for input_mask
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impl Clone for ff_ramp_effect
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impl Clone for cpu_set_t
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impl Clone for timespec
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impl Clone for pthread_cond_t
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impl Clone for timeval
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impl Clone for ff_periodic_effect
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impl Clone for pthread_mutex_t
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impl Clone for statvfs64
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impl Clone for utimbuf
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impl Clone for statfs
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impl Clone for signalfd_siginfo
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impl Clone for linger
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impl Clone for input_id
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impl Clone for utmpx
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impl Clone for flock
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impl Clone for passwd
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impl Clone for pthread_mutexattr_t
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impl Clone for ff_constant_effect
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impl Clone for sysinfo
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impl Clone for ipv6_mreq
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impl Clone for ff_envelope
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impl Clone for winsize
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impl Clone for user_fpregs_struct
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impl Clone for sigval
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impl Clone for sigevent
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impl Clone for input_absinfo
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impl Clone for rlimit64
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impl Clone for stat
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impl Clone for spwd
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impl Clone for mmsghdr
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impl Clone for iovec
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impl Clone for __exit_status
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impl Clone for ff_condition_effect
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impl Clone for mq_attr
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impl Clone for ff_trigger
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impl Clone for _libc_xmmreg
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impl Clone for dirent64
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impl Clone for sockaddr_nl
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impl Clone for pthread_condattr_t
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impl Clone for rlimit
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impl Clone for _libc_fpxreg
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impl Clone for pthread_rwlock_t
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impl Clone for mcontext_t
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impl Clone for input_keymap_entry
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impl Clone for utsname
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impl Clone for msghdr
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impl Clone for if_nameindex
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impl Clone for siginfo_t
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impl Clone for addrinfo
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impl Clone for itimerval
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impl Clone for sockaddr_in6
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impl Clone for sockaddr
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impl Clone for rusage
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impl Clone for sched_param
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impl Clone for sockaddr_in
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impl Clone for sockaddr_storage
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impl Clone for ff_rumble_effect
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impl Clone for stat64
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impl Clone for statvfs
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impl Clone for statfs64
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impl Clone for sigaction
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impl Clone for glob_t
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impl Clone for group
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impl Clone for tms
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impl Clone for shmid_ds
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impl Clone for input_event
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impl Clone for Dl_info
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impl Clone for ifaddrs
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impl Clone for pollfd
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impl Clone for cmsghdr
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impl Clone for ip_mreq
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impl Clone for aiocb
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impl Clone for msginfo
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impl Clone for user
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impl Clone for lconv
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impl Clone for sem_t
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impl Clone for sockaddr_un
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impl Clone for ucred
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impl Clone for stack_t
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impl Clone for dqblk
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impl Clone for user_regs_struct
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impl Clone for glob64_t
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impl Clone for ucontext_t
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impl Clone for sembuf
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impl Clone for tm
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impl Clone for _libc_fpstate
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impl Clone for pthread_attr_t
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impl Clone for in_addr
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impl Clone for ff_replay
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impl Clone for pthread_rwlockattr_t
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impl Clone for msqid_ds
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impl Clone for ipc_perm
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impl Clone for __timeval
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Implementors