std::cell::RefCell
Struct std::cell::RefCell
pub struct RefCell<T> where 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>
[src]
const fn new(value: T) -> RefCell<T>
Creates a new RefCell
containing value
.
Examples
use std::cell::RefCell; let c = RefCell::new(5);
fn into_inner(self) -> T
Consumes the RefCell
, returning the wrapped value.
Examples
use std::cell::RefCell; let c = RefCell::new(5); let five = c.into_inner();
impl<T> RefCell<T> where
T: ?Sized,
[src]
T: ?Sized,
fn borrow(&self) -> Ref<T>
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();
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());
fn try_borrow(&self) -> Result<Ref<T>, BorrowError>
1.13.0
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()); }
fn borrow_mut(&self) -> RefMut<T>
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);
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());
fn try_borrow_mut(&self) -> Result<RefMut<T>, BorrowMutError>
1.13.0
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());
fn as_ptr(&self) -> *mut T
1.12.0
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();
fn get_mut(&mut self) -> &mut T
1.11.0
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 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));
Trait Implementations
impl<T> Eq for RefCell<T> where
T: Eq + ?Sized,
1.2.0
[src]
T: Eq + ?Sized,
impl<T> Default for RefCell<T> where
T: Default,
[src]
T: Default,
fn default() -> RefCell<T>
Creates a RefCell<T>
, with the Default
value for T.
impl<T, U> CoerceUnsized<RefCell<U>> for RefCell<T> where
T: CoerceUnsized<U>,
[src]
T: CoerceUnsized<U>,
impl<T> Send for RefCell<T> where
T: Send + ?Sized,
[src]
T: Send + ?Sized,
impl<T> Debug for RefCell<T> where
T: Debug + ?Sized,
[src]
T: Debug + ?Sized,
fn fmt(&self, f: &mut Formatter) -> Result<(), Error>
Formats the value using the given formatter.
impl<T> !Sync for RefCell<T> where
T: ?Sized,
[src]
T: ?Sized,
impl<T> Ord for RefCell<T> where
T: Ord + ?Sized,
1.10.0
[src]
T: Ord + ?Sized,
fn cmp(&self, other: &RefCell<T>) -> Ordering
This method returns an Ordering
between self
and other
. Read more
impl<T> PartialEq<RefCell<T>> for RefCell<T> where
T: PartialEq<T> + ?Sized,
[src]
T: PartialEq<T> + ?Sized,
fn eq(&self, other: &RefCell<T>) -> bool
This method tests for self
and other
values to be equal, and is used by ==
. Read more
fn ne(&self, other: &Rhs) -> bool
This method tests for !=
.
impl<T> Clone for RefCell<T> where
T: Clone,
[src]
T: Clone,
fn clone(&self) -> RefCell<T>
Returns a copy of the value. Read more
fn clone_from(&mut self, source: &Self)
Performs copy-assignment from source
. Read more
impl<T> PartialOrd<RefCell<T>> for RefCell<T> where
T: PartialOrd<T> + ?Sized,
1.10.0
[src]
T: PartialOrd<T> + ?Sized,
fn partial_cmp(&self, other: &RefCell<T>) -> Option<Ordering>
This method returns an ordering between self
and other
values if one exists. Read more
fn lt(&self, other: &RefCell<T>) -> bool
This method tests less than (for self
and other
) and is used by the <
operator. Read more
fn le(&self, other: &RefCell<T>) -> bool
This method tests less than or equal to (for self
and other
) and is used by the <=
operator. Read more
fn gt(&self, other: &RefCell<T>) -> bool
This method tests greater than (for self
and other
) and is used by the >
operator. Read more
fn ge(&self, other: &RefCell<T>) -> bool
This method tests greater than or equal to (for self
and other
) and is used by the >=
operator. Read more
impl<T> From<T> for RefCell<T>
1.12.0
[src]
fn from(t: T) -> RefCell<T>
Performs the conversion.
© 2010 The Rust Project Developers
Licensed under the Apache License, Version 2.0 or the MIT license, at your option.
https://doc.rust-lang.org/std/cell/struct.RefCell.html