Trait nom::lib::std::ops::Deref1.0.0[−][src]

#[lang = "deref"]
pub trait Deref {
    type Target: ?Sized;
    #[must_use]
    pub fn deref(&self) -> &Self::Target;
}
[−]

Used for immutable dereferencing operations, like *v.

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

Implementing Deref for smart pointers makes accessing the data behind them convenient, which is why they implement Deref. On the other hand, the rules regarding Deref and DerefMut were designed specifically to accommodate smart pointers. Because of this, Deref 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 Deref is invoked implicitly.

More on Deref coercion

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

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 accessible by dereferencing the struct.

use std::ops::Deref;

struct DerefExample<T> {
    value: T
}

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

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

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

Associated Types

type Target: ?Sized[src][−]

The resulting type after dereferencing.

Required methods

#[must_use]
pub fn deref(&self) -> &Self::Target[src][−]

Dereferences the value.

Implementations on Foreign Types

impl<P> Deref for Pin<P> where
    P: Deref, [src][−]

type Target = <P as Deref>::Target

impl<'_, T> Deref for RefMut<'_, T> where
    T: ?Sized, [src][−]

type Target = T

impl<'_, T> Deref for Ref<'_, T> where
    T: ?Sized, [src][−]

type Target = T

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

type Target = VaListImpl<'f>

impl<T, F> Deref for Lazy<T, F> where
    F: FnOnce() -> T, [src][−]

type Target = T

Implementors

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

type Target = T

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

type Target = T

impl<T> Deref for ManuallyDrop<T> where
    T: ?Sized, 1.20.0[src][+]

type Target = T

impl<T: ?Sized + Pointable> Deref for Owned<T>

impl<T> Deref for CachePadded<T>

impl<T: ?Sized> Deref for ShardedLockReadGuard<'_, T>

impl<T: ?Sized> Deref for ShardedLockWriteGuard<'_, T>

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

impl<'a, R: Resources> Deref for AccessGuard<'a, R>

impl<R: Resources> Deref for RawBuffer<R>

impl<R: Resources> Deref for Program<R>

impl<R: Resources> Deref for RawTexture<R>

impl<'a, R: Resources, T: 'a + Copy> Deref for Reader<'a, R, T>

impl<'a, R: Resources, T: 'a + Copy> Deref for Writer<'a, R, T>

impl<T: ContextCurrentState, W> Deref for ContextWrapper<T, W>

impl<P, Container> Deref for ImageBuffer<P, Container> where
    P: Pixel + 'static,
    P::Subpixel: 'static,
    Container: Deref<Target = [P::Subpixel]>, 

impl Deref for IoVec

impl<T> Deref for Symbol<T>

impl<'lib, T> Deref for Symbol<'lib, T>

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

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

impl<'a, R: RawMutex + 'a, G: GetThreadId + 'a, T: ?Sized + 'a> Deref for ReentrantMutexGuard<'a, R, G, T>

impl<'a, R: RawMutex + 'a, G: GetThreadId + 'a, T: ?Sized + 'a> Deref for MappedReentrantMutexGuard<'a, R, G, T>

impl<'a, R: RawRwLock + 'a, T: ?Sized + 'a> Deref for RwLockReadGuard<'a, R, T>

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

impl<'a, R: RawRwLockUpgrade + 'a, T: ?Sized + 'a> Deref for RwLockUpgradableReadGuard<'a, R, T>

impl<'a, R: RawRwLock + 'a, T: ?Sized + 'a> Deref for MappedRwLockReadGuard<'a, R, T>

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

impl Deref for Mmap

impl Deref for MmapMut

impl Deref for UnixReady

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

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

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

impl<A: Array> Deref for SmallVec<A>

impl Deref for ThemedPointer

impl Deref for Underscore

impl Deref for Add

impl Deref for And

impl Deref for At

impl Deref for Bang

impl Deref for Caret

impl Deref for Colon

impl Deref for Comma

impl Deref for Div

impl Deref for Dollar

impl Deref for Dot

impl Deref for Eq

impl Deref for Gt

impl Deref for Lt

impl Deref for Or

impl Deref for Pound

impl Deref for Question

impl Deref for Rem

impl Deref for Semi

impl Deref for Star

impl Deref for Sub

impl Deref for Tilde

impl<'c, 'a> Deref for StepCursor<'c, 'a>

impl Deref for Display

impl<I: Interface> Deref for Attached<I>

impl<I: Interface> Deref for Main<I> where
    I: AsRef<Proxy<I>> + From<Proxy<I>>, 

impl Deref for CursorImageBuffer

impl Deref for WAYLAND_CLIENT_OPTION

impl Deref for WAYLAND_CLIENT_HANDLE

impl Deref for WAYLAND_EGL_OPTION

impl Deref for WAYLAND_EGL_HANDLE

impl<T> Deref for EventLoop<T>