# Struct std::cell::Ref 1.0.0 [−] [src]

    pub struct Ref<'b, T> where
        T: '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

## Trait Implementations

### `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

### `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> 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<'b, T, U> CoerceUnsized<Ref<'b, U>> for Ref<'b, T> where
T: Unsize<U> + ?Sized,
U: ?Sized,`
[src]

# Help

## Keyboard Shortcuts

`?`
  Show this help dialog
`S`
  Focus the search field
`↑`
  Move up in search results
`↓`
  Move down in search results
`↹`
  Switch tab
`⏎`
  Go to active search result
`+`
  Expand all sections
`-`
  Collapse all sections

## Search Tricks

Prefix searches with a type followed by a colon (e.g. `fn:`) to restrict the search to a given type.

Accepted types are: `fn`, `mod`, `struct`, `enum`, `trait`, `type`, `macro`, and `const`.

Search functions by type signature (e.g. `vec -> usize` or `* -> vec`)