std::cell::Ref - Rust
Description: API documentation for the Rust `Ref` struct in crate `std`.
Keywords: rust, rustlang, rust-lang, Ref

# 1.0.0[−][src]Struct std::cell::Ref

    pub struct Ref<'b, T> where
        T: 'b + 'b + ?Sized,  { /* 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> Ref<'b, T> where T: ?Sized,`

[src]

####

`pub fn clone(orig: &Ref<'b, T>) -> Ref<'b, T>`

1.15.0
[src]

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`.

####

`pub fn map<U, F>(orig: Ref<'b, T>, f: F) -> Ref<'b, U> where F: FnOnce(&T) -> &U, U: ?Sized,`

1.8.0
[src]

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

####

`pub fn map_split<U, V, F>(orig: Ref<'b, T>, f: F) -> (Ref<'b, U>, Ref<'b, V>) where F: FnOnce(&T) -> (&U, &V), U: ?Sized, V: ?Sized,`

[src]

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

Split a `Ref` into multiple `Ref`s 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<'b, T> Debug for Ref<'b, T> where T: Debug + ?Sized,`

[src]

####

`fn fmt(&self, f: &mut Formatter) -> Result<(), Error>`

[src]

Formats the value using the given formatter. Read more

###

`impl<'b, T, U> CoerceUnsized<Ref<'b, U>> for Ref<'b, T> where T: Unsize<U> + ?Sized, U: ?Sized,`

[src]

###

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

[src]

#### `type Target = T`

The resulting type after dereferencing.

####
ⓘImportant traits for &'a mut I

### Important traits for &'a mut I

`impl<'a, I> Iterator for &'a mut I where
I: Iterator + ?Sized, type Item = <I as Iterator>::Item;impl<'a, R: Read + ?Sized> Read for &'a mut Rimpl<'a, W: Write + ?Sized> Write for &'a mut W`

`fn deref(&self) -> &T`

[src]

Dereferences the value.

###

`impl<'a, T> Display for Ref<'a, T> where T: Display + ?Sized,`

1.20.0
[src]

####

`fn fmt(&self, f: &mut Formatter) -> Result<(), Error>`

[src]

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> TryFrom for T where T: From<U>,`

[src]

#### `type Error = !`

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

The type returned in the event of a conversion error.

####

`fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>`

[src]

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

Performs the conversion.

###

`impl<T> From for T`

[src]

####

`fn from(t: T) -> T`

[src]

Performs the conversion.

###

`impl<T, U> TryInto for T where U: TryFrom<T>,`

[src]

#### `type Error = <U as TryFrom<T>>::Error`

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

The type returned in the event of a conversion error.

####

`fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>`

[src]

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

Performs the conversion.

###

`impl<T, U> Into for T where U: From<T>,`

[src]

####

`fn into(self) -> U`

[src]

Performs the conversion.

###

`impl<T> Borrow for T where T: ?Sized,`

[src]

####
ⓘImportant traits for &'a mut I

### Important traits for &'a mut I

`impl<'a, I> Iterator for &'a mut I where
I: Iterator + ?Sized, type Item = <I as Iterator>::Item;impl<'a, R: Read + ?Sized> Read for &'a mut Rimpl<'a, W: Write + ?Sized> Write for &'a mut W`

`fn borrow(&self) -> &T`

[src]

Immutably borrows from an owned value. Read more

###

`impl<T> BorrowMut for T where T: ?Sized,`

[src]

####
ⓘImportant traits for &'a mut I

### Important traits for &'a mut I

`impl<'a, I> Iterator for &'a mut I where
I: Iterator + ?Sized, type Item = <I as Iterator>::Item;impl<'a, R: Read + ?Sized> Read for &'a mut Rimpl<'a, W: Write + ?Sized> Write for &'a mut W`

`fn borrow_mut(&mut self) -> &mut T`

[src]

Mutably borrows from an owned value. Read more

###

`impl<T> Any for T where T: 'static + ?Sized,`

[src]

####

`fn get_type_id(&self) -> TypeId`

[src]

🔬 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

###

`impl<T> ToString for T where T: Display + ?Sized,`

[src]

####

`fn to_string(&self) -> String`

[src]

Converts the given value to a `String`. Read more

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