1.0.0[][src]Struct core::cell::Ref

pub struct Ref<'b, T: ?Sized + 'b> { /* fields omitted */ }

Wraps a borrowed reference to a value in a RefCell box. A wrapper type for an immutably borrowed value from a RefCell<T>.

See the module-level documentation for more.

Methods

impl<'b, T: ?Sized> Ref<'b, T>
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Copies a Ref.

The RefCell is already immutably borrowed, so this cannot fail.

This is an associated function that needs to be used as Ref::clone(...). A Clone implementation or a method would interfere with the widespread use of r.borrow().clone() to clone the contents of a RefCell.

Make a new Ref for a component of the borrowed data.

The RefCell 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 RefCell used through Deref.

Examples

use std::cell::{RefCell, Ref};

let c = RefCell::new((5, 'b'));
let b1: Ref<(u32, char)> = c.borrow();
let b2: Ref<u32> = Ref::map(b1, |t| &t.0);
assert_eq!(*b2, 5)Run

🔬 This is a nightly-only experimental API. (refcell_map_split #51476)

Split a Ref into multiple Refs for different components of the borrowed data.

The RefCell is already immutably borrowed, so this cannot fail.

This is an associated function that needs to be used as Ref::map_split(...). A method would interfere with methods of the same name on the contents of a RefCell used through Deref.

Examples

#![feature(refcell_map_split)]
use std::cell::{Ref, RefCell};

let cell = RefCell::new([1, 2, 3, 4]);
let borrow = cell.borrow();
let (begin, end) = Ref::map_split(borrow, |slice| slice.split_at(2));
assert_eq!(*begin, [1, 2]);
assert_eq!(*end, [3, 4]);Run

Trait Implementations

impl<T: ?Sized, '_> Deref for Ref<'_, T>
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The resulting type after dereferencing.

Dereferences the value.

impl<'b, T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<Ref<'b, U>> for Ref<'b, T>
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impl<T: ?Sized + Debug, '_> Debug for Ref<'_, T>
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Formats the value using the given formatter. Read more

impl<T: ?Sized + Display, '_> Display for Ref<'_, T>
1.20.0
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Formats the value using the given formatter. Read more

Auto Trait Implementations

impl<'b, T> !Send for Ref<'b, T>

impl<'b, T> !Sync for Ref<'b, T>

Blanket Implementations

impl<T, U> Into for T where
    U: From<T>, 
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Performs the conversion.

impl<T> From for T
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Performs the conversion.

impl<T, U> TryInto for T where
    U: TryFrom<T>, 
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🔬 This is a nightly-only experimental API. (try_from #33417)

The type returned in the event of a conversion error.

🔬 This is a nightly-only experimental API. (try_from #33417)

Performs the conversion.

impl<T, U> TryFrom for T where
    T: From<U>, 
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🔬 This is a nightly-only experimental API. (try_from #33417)

The type returned in the event of a conversion error.

🔬 This is a nightly-only experimental API. (try_from #33417)

Performs the conversion.

impl<T> Borrow for T where
    T: ?Sized
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Immutably borrows from an owned value. Read more

impl<T> BorrowMut for T where
    T: ?Sized
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Mutably borrows from an owned value. Read more

impl<T> Any for T where
    T: 'static + ?Sized
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🔬 This is a nightly-only experimental API. (get_type_id #27745)

this method will likely be replaced by an associated static

Gets the TypeId of self. Read more