Trait rocket::mtls::oid::asn1_rs::nom::lib::std::ops::DerefMut

pub trait DerefMut: Deref {
    // Required method
    fn deref_mut(&mut self) -> &mut Self::Target;
}

Available on crate feature mtls only.

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.

Violating these requirements is a logic error. The behavior resulting from a logic error is not specified, but users of the trait must ensure that such logic errors do not result in undefined behavior. This means that unsafe code must not rely on the correctness of this method.

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.value);

Required Methods

fn deref_mut(&mut self) -> &mut Self::Target

Mutably dereferences the value.

Implementors

impl DerefMut for NamedFile

impl DerefMut for String

impl DerefMut for OsString

impl DerefMut for PathBuf

impl DerefMut for BytesMut

impl DerefMut for ClientConnection

impl DerefMut for Connection

impl DerefMut for Document

impl DerefMut for InlinableString

impl DerefMut for InlineString

impl DerefMut for ServerConnection

impl<'a> DerefMut for IoSliceMut<'a>

impl<'a> DerefMut for socket2::MaybeUninitSlice<'a>

impl<'a> DerefMut for MaybeUninitSlice<'a>

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

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

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

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

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

impl<'a, T> DerefMut for tokio::sync::mutex::MappedMutexGuard<'a, T>where T: ?Sized,

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

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

impl<'a, T> DerefMut for SpinMutexGuard<'a, T>where T: ?Sized,

impl<'c> DerefMut for rocket::local::asynchronous::LocalRequest<'c>

impl<'c> DerefMut for rocket::local::blocking::LocalRequest<'c>

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

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

impl<'v> DerefMut for Errors<'v>

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

impl<B, T> DerefMut for Ref<B, [T]>where B: ByteSliceMut, T: FromBytes + AsBytes,

impl<B, T> DerefMut for Ref<B, T>where B: ByteSliceMut, T: FromBytes + AsBytes,

impl<I> DerefMut for Pear<I>where I: Input,

impl<K, V, S> DerefMut for AHashMap<K, V, S>

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

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

impl<T> !DerefMut for &Twhere T: ?Sized,

impl<T> DerefMut for &mut Twhere T: ?Sized,

impl<T> DerefMut for Capped<T>

impl<T> DerefMut for Form<T>

impl<T> DerefMut for Lenient<T>

impl<T> DerefMut for Strict<T>

impl<T> DerefMut for Json<T>

Available on crate feature json only.

impl<T> DerefMut for MsgPack<T>

Available on crate feature msgpack only.

impl<T> DerefMut for ThinBox<T>where T: ?Sized,

impl<T> DerefMut for ManuallyDrop<T>where T: ?Sized,

impl<T> DerefMut for UniqueRc<T>

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

impl<T> DerefMut for AssertUnwindSafe<T>

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

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

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

impl<T> DerefMut for tokio::sync::mutex::OwnedMutexGuard<T>where T: ?Sized,

impl<T> DerefMut for OwnedRwLockWriteGuard<T>where T: ?Sized,

impl<T> DerefMut for tokio::sync::rwlock::write_guard::RwLockWriteGuard<'_, T>where T: ?Sized,

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

impl<T> DerefMut for ConnectionCommon<T>

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

impl<T> DerefMut for OwnedMutexGuard<T>where T: ?Sized,

impl<T> DerefMut for Unalign<T>where T: Unaligned,

impl<T, A> DerefMut for rocket::mtls::oid::asn1_rs::nom::lib::std::boxed::Box<T, A>where A: Allocator, T: ?Sized,

impl<T, A> DerefMut for PeekMut<'_, T, A>where T: Ord, A: Allocator,

impl<T, A> DerefMut for rocket::mtls::oid::asn1_rs::nom::lib::std::vec::Vec<T, A>where A: Allocator,

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

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

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

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

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

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

impl<T, S> DerefMut for AHashSet<T, S>

impl<T, U> DerefMut for OwnedMappedMutexGuard<T, U>where T: ?Sized, U: ?Sized,

impl<T, U> DerefMut for OwnedRwLockMappedWriteGuard<T, U>where T: ?Sized, U: ?Sized,

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