1.0.0[−][src]Trait nom::lib::std::ops::Deref
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
on non-pointer types 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] book as well as the reference sections on [the dereference operator] ref-deref-op, 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
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impl<'a> Deref for IoSlice<'a>
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impl Deref for OsString
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impl<'a> Deref for IoSliceMut<'a>
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impl Deref for PathBuf
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impl<'_, T> Deref for RwLockWriteGuard<'_, T> where
T: ?Sized,
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T: ?Sized,
impl<T> Deref for AssertUnwindSafe<T>
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impl<'_, T> Deref for MutexGuard<'_, 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 CString
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impl<'_, T> Deref for &'_ T where
T: ?Sized,
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T: ?Sized,
impl<'_, T> Deref for Ref<'_, 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> Deref for RefMut<'_, T> where
T: ?Sized,
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T: ?Sized,
impl<P> Deref for Pin<P> where
P: Deref,
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P: Deref,
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 Deref for Literal
impl<A> Deref for StackVec<A> where
A: Array,
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A: Array,
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,
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T: Ord,
impl<T> Deref for ManuallyDrop<T> where
T: ?Sized,
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T: ?Sized,
impl<T> Deref for Box<T> where
T: ?Sized,
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T: ?Sized,