1.0.0[][src]Trait af_lib::prelude::DerefMut

#[lang = "deref_mut"]pub trait DerefMut: Deref {
    pub fn deref_mut(&mut self) -> &mut Self::Target;
}

Used for mutable dereferencing operations, like in *v = 1;.

In addition to being used for explicit dereferencing operations with the (unary) * operator in mutable contexts, DerefMut is also used implicitly by the compiler in many circumstances. This mechanism is called 'Deref coercion'. In immutable contexts, Deref is used.

Implementing DerefMut for smart pointers makes mutating the data behind them convenient, which is why they implement DerefMut. On the other hand, the rules regarding Deref and DerefMut were designed specifically to accommodate smart pointers. Because of this, DerefMut should only be implemented for smart pointers to avoid confusion.

For similar reasons, this trait should never fail. Failure during dereferencing can be extremely confusing when DerefMut is invoked implicitly.

More on Deref coercion

If T implements DerefMut<Target = U>, and x is a value of type T, then:

  • In mutable contexts, *x (where T is neither a reference nor a raw pointer) is equivalent to *DerefMut::deref_mut(&mut x).
  • Values of type &mut T are coerced to values of type &mut U
  • T implicitly implements all the (mutable) methods of the type U.

For more details, visit the chapter in The Rust Programming Language as well as the reference sections on the dereference operator, method resolution and type coercions.

Examples

A struct with a single field which is modifiable by dereferencing the struct.

use std::ops::{Deref, DerefMut};

struct DerefMutExample<T> {
    value: T
}

impl<T> Deref for DerefMutExample<T> {
    type Target = T;

    fn deref(&self) -> &Self::Target {
        &self.value
    }
}

impl<T> DerefMut for DerefMutExample<T> {
    fn deref_mut(&mut self) -> &mut Self::Target {
        &mut self.value
    }
}

let mut x = DerefMutExample { value: 'a' };
*x = 'b';
assert_eq!('b', *x);

Required methods

pub fn deref_mut(&mut self) -> &mut Self::Target[src]

Mutably dereferences the value.

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Implementations on Foreign Types

impl DerefMut for OsString[src]

impl<'_, T> DerefMut for RwLockWriteGuard<'_, T> where
    T: ?Sized
[src]

impl<'_, T> DerefMut for MutexGuard<'_, T> where
    T: ?Sized
[src]

impl<'a> DerefMut for IoSliceMut<'a>[src]

impl<'a, 'f> DerefMut for VaList<'a, 'f> where
    'f: 'a, 
[src]

impl<'_, T> DerefMut for &'_ mut T where
    T: ?Sized
[src]

impl<'_, T> !DerefMut for &'_ T where
    T: ?Sized
[src]

impl<T, A> DerefMut for Box<T, A> where
    T: ?Sized,
    A: Allocator
[src]

impl<'_, T> DerefMut for PeekMut<'_, T> where
    T: Ord
[src]

impl DerefMut for String[src]

impl<T, A> DerefMut for Vec<T, A> where
    A: Allocator
[src]

impl<T> DerefMut for CachePadded<T>

impl<'a, R, T> DerefMut for MutexGuard<'a, R, T> where
    T: 'a + ?Sized,
    R: 'a + RawMutex, 

impl<'a, R, T> DerefMut for MappedRwLockWriteGuard<'a, R, T> where
    T: 'a + ?Sized,
    R: 'a + RawRwLock, 

impl<'a, R, T> DerefMut for RwLockWriteGuard<'a, R, T> where
    T: 'a + ?Sized,
    R: 'a + RawRwLock, 

impl<'a, R, T> DerefMut for MappedMutexGuard<'a, R, T> where
    T: 'a + ?Sized,
    R: 'a + RawMutex, 

impl<T, F, S> DerefMut for ScopeGuard<T, F, S> where
    F: FnOnce(T),
    S: Strategy
[src]

impl<A> DerefMut for SmallVec<A> where
    A: Array, 

impl DerefMut for Literal

impl<'rwlock, T> DerefMut for RwLockWriteGuard<'rwlock, T> where
    T: ?Sized

impl<'a, K, V, S> DerefMut for RefMut<'a, K, V, S> where
    S: BuildHasher,
    K: Eq + Hash

impl<'a, K, V, S> DerefMut for RefMutMulti<'a, K, V, S> where
    S: BuildHasher,
    K: Eq + Hash

impl DerefMut for BytesMut[src]

impl DerefMut for Digest

impl<T, N> DerefMut for GenericArray<T, N> where
    N: ArrayLength<T>, 

impl<'s, T> DerefMut for SliceVec<'s, T>

impl<A> DerefMut for TinyVec<A> where
    A: Array, 

impl<A> DerefMut for ArrayVec<A> where
    A: Array, 

impl<A, T> DerefMut for InlineArray<A, T>

impl<A, N> DerefMut for Chunk<A, N> where
    N: ChunkLength<A>, 

impl<'_, T> DerefMut for MutexGuard<'_, T> where
    T: ?Sized

impl<T> DerefMut for MutexGuardArc<T> where
    T: ?Sized

impl<'_, T> DerefMut for MutexGuard<'_, T> where
    T: ?Sized
[src]

impl<'_, T> DerefMut for RwLockWriteGuard<'_, T> where
    T: ?Sized
[src]

impl<T> DerefMut for OwnedMutexGuard<T> where
    T: ?Sized
[src]

impl DerefMut for X509Algorithm[src]

impl DerefMut for CmsContentInfo[src]

impl DerefMut for SslConnectorBuilder[src]

impl DerefMut for GeneralName[src]

impl DerefMut for Asn1Time[src]

impl DerefMut for Conf[src]

impl DerefMut for SrtpProtectionProfile[src]

impl DerefMut for SslAcceptorBuilder[src]

impl DerefMut for EcGroup[src]

impl DerefMut for OcspBasicResponse[src]

impl<T> DerefMut for Stack<T> where
    T: Stackable
[src]

impl DerefMut for X509StoreContext[src]

impl DerefMut for SslContext[src]

impl DerefMut for Asn1GeneralizedTime[src]

impl DerefMut for DigestBytes[src]

impl DerefMut for Ssl[src]

impl DerefMut for X509Store[src]

impl DerefMut for Asn1BitString[src]

impl DerefMut for X509Object[src]

impl<T> DerefMut for X509LookupMethod<T>[src]

impl DerefMut for BigNum[src]

impl DerefMut for Asn1Object[src]

impl DerefMut for Pkcs7[src]

impl DerefMut for Asn1String[src]

impl DerefMut for X509Extension[src]

impl DerefMut for EcdsaSig[src]

impl DerefMut for X509Name[src]

impl DerefMut for BigNumContext[src]

impl DerefMut for Pkcs12[src]

impl DerefMut for X509NameEntry[src]

impl DerefMut for Asn1Integer[src]

impl DerefMut for EcPoint[src]

impl<T> DerefMut for EcKey<T>[src]

impl DerefMut for OcspCertId[src]

impl<T> DerefMut for PKey<T>[src]

impl DerefMut for ConnectConfiguration[src]

impl DerefMut for X509[src]

impl<T> DerefMut for Dsa<T>[src]

impl<T> DerefMut for Dh<T>[src]

impl DerefMut for X509StoreBuilder[src]

impl DerefMut for SslCipher[src]

impl DerefMut for X509Req[src]

impl<T> DerefMut for Rsa<T>[src]

impl<T> DerefMut for X509Lookup<T>[src]

impl DerefMut for X509VerifyParam[src]

impl DerefMut for SslSession[src]

impl DerefMut for OcspOneReq[src]

impl DerefMut for OcspRequest[src]

impl DerefMut for OcspResponse[src]

impl DerefMut for OpensslString[src]

impl<'_, T> DerefMut for MutexGuard<'_, T> where
    T: ?Sized

impl<'_, T, U> DerefMut for MappedMutexGuard<'_, T, U> where
    T: ?Sized,
    U: ?Sized

impl<S> DerefMut for BlockingStream<S> where
    S: Unpin + Stream

impl<A> DerefMut for SmallString<A> where
    A: Array<Item = u8>, 

impl<T> DerefMut for Values<T>

impl DerefMut for BytesMut[src]

impl<'_, T> DerefMut for MutexGuard<'_, T> where
    T: ?Sized
[src]

impl<'_, T> DerefMut for RwLockWriteGuard<'_, T> where
    T: ?Sized
[src]

impl<T> DerefMut for OwnedMutexGuard<T> where
    T: ?Sized
[src]

impl DerefMut for UnixReady[src]

impl DerefMut for IoVec

impl<'a, T> DerefMut for Locked<'a, T>[src]

impl<S> DerefMut for UniCase<S>[src]

impl<S> DerefMut for Ascii<S>[src]

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Implementors

impl<'_, T> DerefMut for af_lib::prelude::af_core::test::prelude::cell::RefMut<'_, T> where
    T: ?Sized
[src]

impl<L, R> DerefMut for Either<L, R> where
    L: DerefMut,
    R: DerefMut<Target = <L as Deref>::Target>, 
[src]

impl<P> DerefMut for Pin<P> where
    P: DerefMut,
    <P as Deref>::Target: Unpin
[src]

impl<T> DerefMut for AssertUnwindSafe<T>[src]

impl<T> DerefMut for ManuallyDrop<T> where
    T: ?Sized
[src]

impl<T, E> DerefMut for TryJoin<T, E>[src]

impl<T, F> DerefMut for af_lib::lazy::Lazy<T, F> where
    F: FnOnce() -> T, 

impl<T, F> DerefMut for af_lib::prelude::Lazy<T, F> where
    F: FnOnce() -> T, 

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