Trait nom::lib::std::ops::Deref 1.0.0[−][src]
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
(whereT
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 typeU
.
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
Loading content...Required methods
Loading content...Implementations on Foreign Types
impl<'_, T> Deref for MutexGuard<'_, T> where
T: ?Sized,
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T: ?Sized,
impl<T, F> Deref for SyncLazy<T, F> where
F: FnOnce() -> T,
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F: FnOnce() -> T,
impl<'a> Deref for IoSlice<'a>
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impl<'_, T> Deref for RwLockWriteGuard<'_, T> where
T: ?Sized,
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T: ?Sized,
impl<'_, T> Deref for RwLockReadGuard<'_, T> where
T: ?Sized,
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T: ?Sized,
impl Deref for PathBuf
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impl Deref for CString
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impl<'a> Deref for IoSliceMut<'a>
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impl<T> Deref for AssertUnwindSafe<T>
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impl Deref for OsString
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impl<'_, T> Deref for RefMut<'_, T> where
T: ?Sized,
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T: ?Sized,
impl<'_, T> Deref for &'_ mut T where
T: ?Sized,
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T: ?Sized,
impl<T, F> Deref for Lazy<T, F> where
F: FnOnce() -> T,
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F: FnOnce() -> T,
impl<P> Deref for Pin<P> where
P: Deref,
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P: Deref,
impl<'_, T> Deref for &'_ T where
T: ?Sized,
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T: ?Sized,
impl<'a, 'f> Deref for VaList<'a, 'f> where
'f: 'a,
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'f: 'a,
type Target = VaListImpl<'f>
pub fn deref(&self) -> &VaListImpl<'f>
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impl<'_, T> Deref for Ref<'_, T> where
T: ?Sized,
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T: ?Sized,
impl<T> Deref for Arc<T> where
T: ?Sized,
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T: ?Sized,
impl<T> Deref for Rc<T> where
T: ?Sized,
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T: ?Sized,
impl<O, T> Deref for BitBox<O, T> where
O: BitOrder,
T: BitStore,
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O: BitOrder,
T: BitStore,
impl<O, T> Deref for BitVec<O, T> where
O: BitOrder,
T: BitStore,
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O: BitOrder,
T: BitStore,
impl<'_, O, T> Deref for BitMut<'_, O, T> where
O: BitOrder,
T: BitStore,
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O: BitOrder,
T: BitStore,
impl<O, V> Deref for BitArray<O, V> where
O: BitOrder,
V: BitView,
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O: BitOrder,
V: BitView,
type Target = BitSlice<O, <V as BitView>::Store>
pub fn deref(&self) -> &<BitArray<O, V> as Deref>::Target
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impl<T> Deref for FmtPointer<T> where
T: Pointer,
T: Pointer,
impl<T> Deref for FmtUpperHex<T> where
T: UpperHex,
T: UpperHex,
impl<T> Deref for FmtUpperExp<T> where
T: UpperExp,
T: UpperExp,
impl<T> Deref for FmtLowerExp<T> where
T: LowerExp,
T: LowerExp,
impl<T> Deref for FmtLowerHex<T> where
T: LowerHex,
T: LowerHex,
impl<T> Deref for FmtDisplay<T> where
T: Display,
T: Display,
impl<T> Deref for FmtOctal<T> where
T: Octal,
T: Octal,
impl<T> Deref for FmtBinary<T> where
T: Binary,
T: Binary,
impl<A> Deref for ArrayString<A> where
A: Array<Item = u8> + Copy,
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A: Array<Item = u8> + Copy,
impl<A> Deref for ArrayVec<A> where
A: Array,
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A: Array,
impl Deref for Literal
impl<T, F> Deref for Lazy<T, F> where
F: FnOnce() -> T,
F: FnOnce() -> T,
impl<T, F> Deref for Lazy<T, F> where
F: FnOnce() -> T,
Loading content...F: FnOnce() -> T,
Implementors
impl Deref for String
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impl<'_, B> Deref for Cow<'_, B> where
B: ToOwned + ?Sized,
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B: ToOwned + ?Sized,
impl<'_, T> Deref for PeekMut<'_, T> where
T: Ord,
1.12.0[src]
T: Ord,
impl<T> Deref for ManuallyDrop<T> where
T: ?Sized,
1.20.0[src]
T: ?Sized,
impl<T, A> Deref for Box<T, A> where
T: ?Sized,
A: Allocator,
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T: ?Sized,
A: Allocator,
impl<T, A> Deref for Vec<T, A> where
A: Allocator,
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A: Allocator,