Trait sp_std::ops::Deref

pub trait Deref {
    type Target: ?Sized;
    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:

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

The resulting type after dereferencing.

Required methods

fn deref(&self) -> &Self::Target

Dereferences the value.

Implementations on Foreign Types

impl<T> Deref for AssertUnwindSafe<T>

type Target = T

pub fn deref(&self) -> &T

impl<'a> Deref for IoSlice<'a>

type Target = [u8]

pub fn deref(&self) -> &[u8]

impl Deref for OsString

type Target = OsStr

pub fn deref(&self) -> &OsStr

impl<'a> Deref for IoSliceMut<'a>

type Target = [u8]

pub fn deref(&self) -> &[u8]

impl Deref for PathBuf

type Target = Path

pub fn deref(&self) -> &Path

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

type Target = T

pub fn deref(&self) -> &T

impl Deref for CString

type Target = CStr

pub fn deref(&self) -> &CStr

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

type Target = T

pub fn deref(&self) -> &T

impl<P> Deref for Pin<P> where
    P: Deref, 

type Target = <P as Deref>::Target

pub fn deref(&self) -> &<P as Deref>::Target

impl<'_, T> Deref for &'_ mut T where
    T: ?Sized, 

type Target = T

pub fn deref(&self) -> &T

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

type Target = VaListImpl<'f>

pub fn deref(&self) -> &VaListImpl<'f>

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

type Target = T

pub fn deref(&self) -> &T

impl Deref for String

type Target = str

pub fn deref(&self) -> &str

impl<'_, T> Deref for PeekMut<'_, T> where
    T: Ord, 

type Target = T

pub fn deref(&self) -> &T

Implementors

impl<'_, B> Deref for Cow<'_, B> where
    B: ToOwned + ?Sized, 

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

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

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

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

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

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

impl<T> Deref for Rc<T> where
    T: ?Sized, 

impl<T> Deref for Arc<T> where
    T: ?Sized, 

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

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

impl<K, V, S> Deref for BoundedBTreeMap<K, V, S> where     K: Ord,

impl<T, S> Deref for BoundedBTreeSet<T, S> where     T: Ord,

impl<T, S> Deref for BoundedVec<T, S>

impl<T, S> Deref for WeakBoundedVec<T, S>

impl Deref for KUSAMA_STATE_DISTRIBUTION

impl<T: Config<I>, I: 'static> Deref for ExtraMutator<T, I>

impl<AccountId, C> Deref for BalanceSwapAction<AccountId, C> where     C: ReservableCurrency<AccountId>,

impl<T: Config> Deref for SignedSubmissions<T>

impl Deref for Signature

impl<H, T> Deref for Compact<H, T>

impl<'a, T> Deref for SharedDataLocked<'a, T>

impl Deref for Config

impl<T> Deref for SlotDuration<T>

impl<'a, T> Deref for ApiRef<'a, T>

impl Deref for Signature

impl Deref for Signature

impl Deref for Signature

impl Deref for InherentDataProvider

impl Deref for InherentDataProvider

impl Deref for Slot

impl Deref for VRFOutput

impl Deref for VRFProof

impl Deref for Public

impl Deref for OffchainWorkerExt

impl Deref for OffchainDbExt

impl Deref for TransactionPoolExt

impl Deref for Public

impl Deref for ReadRuntimeVersionExt

impl Deref for TaskExecutorExt

impl Deref for RuntimeSpawnExt

impl Deref for Bytes

impl Deref for OpaqueMetadata

impl Deref for VerificationExt

impl Deref for Keyring

impl Deref for Keyring

impl Deref for KeystoreExt

impl<Xt> Deref for ExtrinsicWrapper<Xt>

impl Deref for PrefixedStorageKey

impl Deref for Timestamp

impl Deref for InherentDataProvider

impl Deref for TOKIO_THREADS_TOTAL

impl Deref for TOKIO_THREADS_ALIVE

impl Deref for UNBOUNDED_CHANNELS_COUNTER