Struct core::cell::RefCell1.0.0 [] [src]

pub struct RefCell<T: ?Sized> { /* fields omitted */ }

A mutable memory location with dynamically checked borrow rules

See the module-level documentation for more.

Methods

impl<T> RefCell<T>
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Creates a new RefCell containing value.

Examples

use std::cell::RefCell;

let c = RefCell::new(5);Run

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Consumes the RefCell, returning the wrapped value.

Examples

use std::cell::RefCell;

let c = RefCell::new(5);

let five = c.into_inner();Run

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🔬 This is a nightly-only experimental API. (refcell_replace_swap #43570)

Replaces the wrapped value with a new one, returning the old value, without deinitializing either one.

This function corresponds to std::mem::replace.

Examples

#![feature(refcell_replace_swap)]
use std::cell::RefCell;
let c = RefCell::new(5);
let u = c.replace(6);
assert_eq!(u, 5);
assert_eq!(c, RefCell::new(6));Run

Panics

This function will panic if the RefCell has any outstanding borrows, whether or not they are full mutable borrows.

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🔬 This is a nightly-only experimental API. (refcell_replace_swap #43570)

Swaps the wrapped value of self with the wrapped value of other, without deinitializing either one.

This function corresponds to std::mem::swap.

Examples

#![feature(refcell_replace_swap)]
use std::cell::RefCell;
let c = RefCell::new(5);
let d = RefCell::new(6);
c.swap(&d);
assert_eq!(c, RefCell::new(6));
assert_eq!(d, RefCell::new(5));Run

Panics

This function will panic if either RefCell has any outstanding borrows, whether or not they are full mutable borrows.

impl<T: ?Sized> RefCell<T>
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Immutably borrows the wrapped value.

The borrow lasts until the returned Ref exits scope. Multiple immutable borrows can be taken out at the same time.

Panics

Panics if the value is currently mutably borrowed. For a non-panicking variant, use try_borrow.

Examples

use std::cell::RefCell;

let c = RefCell::new(5);

let borrowed_five = c.borrow();
let borrowed_five2 = c.borrow();Run

An example of panic:

use std::cell::RefCell;
use std::thread;

let result = thread::spawn(move || {
   let c = RefCell::new(5);
   let m = c.borrow_mut();

   let b = c.borrow(); // this causes a panic
}).join();

assert!(result.is_err());Run

1.13.0
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Immutably borrows the wrapped value, returning an error if the value is currently mutably borrowed.

The borrow lasts until the returned Ref exits scope. Multiple immutable borrows can be taken out at the same time.

This is the non-panicking variant of borrow.

Examples

use std::cell::RefCell;

let c = RefCell::new(5);

{
    let m = c.borrow_mut();
    assert!(c.try_borrow().is_err());
}

{
    let m = c.borrow();
    assert!(c.try_borrow().is_ok());
}Run

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Mutably borrows the wrapped value.

The borrow lasts until the returned RefMut exits scope. The value cannot be borrowed while this borrow is active.

Panics

Panics if the value is currently borrowed. For a non-panicking variant, use try_borrow_mut.

Examples

use std::cell::RefCell;

let c = RefCell::new(5);

*c.borrow_mut() = 7;

assert_eq!(*c.borrow(), 7);Run

An example of panic:

use std::cell::RefCell;
use std::thread;

let result = thread::spawn(move || {
   let c = RefCell::new(5);
   let m = c.borrow();

   let b = c.borrow_mut(); // this causes a panic
}).join();

assert!(result.is_err());Run

1.13.0
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Mutably borrows the wrapped value, returning an error if the value is currently borrowed.

The borrow lasts until the returned RefMut exits scope. The value cannot be borrowed while this borrow is active.

This is the non-panicking variant of borrow_mut.

Examples

use std::cell::RefCell;

let c = RefCell::new(5);

{
    let m = c.borrow();
    assert!(c.try_borrow_mut().is_err());
}

assert!(c.try_borrow_mut().is_ok());Run

1.12.0
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Returns a raw pointer to the underlying data in this cell.

Examples

use std::cell::RefCell;

let c = RefCell::new(5);

let ptr = c.as_ptr();Run

1.11.0
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Returns a mutable reference to the underlying data.

This call borrows RefCell mutably (at compile-time) so there is no need for dynamic checks.

However be cautious: this method expects self to be mutable, which is generally not the case when using a RefCell. Take a look at the borrow_mut method instead if self isn't mutable.

Also, please be aware that this method is only for special circumstances and is usually not what you want. In case of doubt, use borrow_mut instead.

Examples

use std::cell::RefCell;

let mut c = RefCell::new(5);
*c.get_mut() += 1;

assert_eq!(c, RefCell::new(6));Run

Trait Implementations

impl<T: ?Sized> Send for RefCell<T> where
    T: Send
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impl<T: ?Sized> !Sync for RefCell<T>
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impl<T: Clone> Clone for RefCell<T>
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Returns a copy of the value. Read more

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Performs copy-assignment from source. Read more

impl<T: Default> Default for RefCell<T>
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Creates a RefCell<T>, with the Default value for T.

impl<T: ?Sized + PartialEq> PartialEq for RefCell<T>
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This method tests for self and other values to be equal, and is used by ==. Read more

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This method tests for !=.

impl<T: ?Sized + Eq> Eq for RefCell<T>
1.2.0
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impl<T: ?Sized + PartialOrd> PartialOrd for RefCell<T>
1.10.0
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This method returns an ordering between self and other values if one exists. Read more

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This method tests less than (for self and other) and is used by the < operator. Read more

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This method tests less than or equal to (for self and other) and is used by the <= operator. Read more

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This method tests greater than (for self and other) and is used by the > operator. Read more

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This method tests greater than or equal to (for self and other) and is used by the >= operator. Read more

impl<T: ?Sized + Ord> Ord for RefCell<T>
1.10.0
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This method returns an Ordering between self and other. Read more

1.21.0
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Compares and returns the maximum of two values. Read more

1.21.0
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Compares and returns the minimum of two values. Read more

impl<T> From<T> for RefCell<T>
1.12.0
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Performs the conversion.

impl<T: CoerceUnsized<U>, U> CoerceUnsized<RefCell<U>> for RefCell<T>
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impl<T: CoerceUnsized<U>, U> CoerceUnsized<RefCell<U>> for RefCell<T>
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impl<T: ?Sized + Debug> Debug for RefCell<T>
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Formats the value using the given formatter.