Struct oxygengine_core::ecs::shred::cell::Ref [−][src]
An immutable reference to data in a TrustCell
.
Access the value via std::ops::Deref
(e.g. *val
)
Implementations
impl<'a, T> Ref<'a, T> where
T: ?Sized,
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T: ?Sized,
pub fn map<U, F>(self, f: F) -> Ref<'a, U> where
F: FnOnce(&T) -> &U,
U: ?Sized,
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F: FnOnce(&T) -> &U,
U: ?Sized,
Makes a new Ref
for a component of the borrowed data which preserves
the existing borrow.
The TrustCell
is already immutably borrowed, so this cannot fail.
This is an associated function that needs to be used as Ref::map(...)
.
A method would interfere with methods of the same name on the contents
of a Ref
used through Deref
. Further this preserves the borrow of
the value and hence does the proper cleanup when it’s dropped.
Examples
This can be used to avoid pointer indirection when a boxed item is
stored in the TrustCell
.
use shred::cell::{Ref, TrustCell}; let cb = TrustCell::new(Box::new(5)); // Borrowing the cell causes the `Ref` to store a reference to the `Box`, which is a // pointer to the value on the heap, not the actual value. let boxed_ref: Ref<'_, Box<usize>> = cb.borrow(); assert_eq!(**boxed_ref, 5); // Notice the double deref to get the actual value. // By using `map` we can let `Ref` store a reference directly to the value on the heap. let pure_ref: Ref<'_, usize> = Ref::map(boxed_ref, Box::as_ref); assert_eq!(*pure_ref, 5);
We can also use map
to get a reference to a sub-part of the borrowed
value.
let c = TrustCell::new((5, 'b')); let b1: Ref<'_, (u32, char)> = c.borrow(); let b2: Ref<'_, u32> = Ref::map(b1, |t| &t.0); assert_eq!(*b2, 5);
Trait Implementations
impl<'a, T> Clone for Ref<'a, T> where
T: ?Sized,
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T: ?Sized,
impl<'a, T> Debug for Ref<'a, T> where
T: 'a + Debug + ?Sized,
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T: 'a + Debug + ?Sized,
impl<'a, T> Deref for Ref<'a, T> where
T: ?Sized,
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T: ?Sized,
impl<'a, T> Drop for Ref<'a, T> where
T: ?Sized,
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T: ?Sized,
Auto Trait Implementations
impl<'a, T: ?Sized> RefUnwindSafe for Ref<'a, T> where
T: RefUnwindSafe,
T: RefUnwindSafe,
impl<'a, T: ?Sized> Send for Ref<'a, T> where
T: Sync,
T: Sync,
impl<'a, T: ?Sized> Sync for Ref<'a, T> where
T: Sync,
T: Sync,
impl<'a, T: ?Sized> Unpin for Ref<'a, T>
impl<'a, T: ?Sized> UnwindSafe for Ref<'a, T> where
T: RefUnwindSafe,
T: RefUnwindSafe,
Blanket Implementations
impl<T> Any for T where
T: 'static + ?Sized,
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T: 'static + ?Sized,
impl<T> Any for T where
T: Any,
T: Any,
pub fn get_type_id(&self) -> TypeId
impl<T> Borrow<T> for T where
T: ?Sized,
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T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
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T: ?Sized,
pub fn borrow_mut(&mut self) -> &mut T
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impl<T> Event for T where
T: Send + Sync + 'static,
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T: Send + Sync + 'static,
impl<T> From<T> for T
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impl<T, U> Into<U> for T where
U: From<T>,
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U: From<T>,
impl<T> Resource for T where
T: Any,
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T: Any,
impl<T> ToOwned for T where
T: Clone,
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T: Clone,
type Owned = T
The resulting type after obtaining ownership.
pub fn to_owned(&self) -> T
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pub fn clone_into(&self, target: &mut T)
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impl<T, U> TryFrom<U> for T where
U: Into<T>,
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U: Into<T>,
type Error = Infallible
The type returned in the event of a conversion error.
pub fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>
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impl<T, U> TryInto<U> for T where
U: TryFrom<T>,
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U: TryFrom<T>,