pub struct RefCell<T> where
T: ?Sized, { /* fields omitted */ }
Creates a new RefCell
containing value
.
use std::cell::RefCell;
let c = RefCell::new(5);Run
Consumes the RefCell
, returning the wrapped value.
use std::cell::RefCell;
let c = RefCell::new(5);
let five = c.into_inner();Run
Replaces the wrapped value with a new one, returning the old value,
without deinitializing either one.
This function corresponds to std::mem::replace
.
Panics if the value is currently borrowed.
use std::cell::RefCell;
let cell = RefCell::new(5);
let old_value = cell.replace(6);
assert_eq!(old_value, 5);
assert_eq!(cell, RefCell::new(6));Run
🔬 This is a nightly-only experimental API. (
refcell_replace_swap
#43570)
Replaces the wrapped value with a new one computed from f
, returning
the old value, without deinitializing either one.
This function corresponds to std::mem::replace
.
Panics if the value is currently borrowed.
#![feature(refcell_replace_swap)]
use std::cell::RefCell;
let cell = RefCell::new(5);
let old_value = cell.replace_with(|&mut old| old + 1);
assert_eq!(old_value, 5);
assert_eq!(cell, RefCell::new(6));Run
Swaps the wrapped value of self
with the wrapped value of other
,
without deinitializing either one.
This function corresponds to std::mem::swap
.
Panics if the value in either RefCell
is currently borrowed.
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
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 if the value is currently mutably borrowed. For a non-panicking variant, use
try_borrow
.
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();
}).join();
assert!(result.is_err());Run
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
.
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
Mutably borrows the wrapped value.
The borrow lasts until the returned RefMut
or all RefMut
s derived
from it exit scope. The value cannot be borrowed while this borrow is
active.
Panics if the value is currently borrowed. For a non-panicking variant, use
try_borrow_mut
.
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();
}).join();
assert!(result.is_err());Run
Mutably borrows the wrapped value, returning an error if the value is currently borrowed.
The borrow lasts until the returned RefMut
or all RefMut
s derived
from it exit scope. The value cannot be borrowed while this borrow is
active.
This is the non-panicking variant of borrow_mut
.
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
Returns a raw pointer to the underlying data in this cell.
use std::cell::RefCell;
let c = RefCell::new(5);
let ptr = c.as_ptr();Run
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.
use std::cell::RefCell;
let mut c = RefCell::new(5);
*c.get_mut() += 1;
assert_eq!(c, RefCell::new(6));Run
Formats the value using the given formatter. Read more
Panics if the value is currently mutably borrowed.
Performs copy-assignment from source
. Read more
Panics if the value in either RefCell
is currently borrowed.
Panics if the value in either RefCell
is currently borrowed.
Panics if the value in either RefCell
is currently borrowed.
Panics if the value in either RefCell
is currently borrowed.
Panics if the value in either RefCell
is currently borrowed.
Panics if the value in either RefCell
is currently borrowed.
fn max(self, other: Self) -> Self | 1.21.0 [src] |
Compares and returns the maximum of two values. Read more
fn min(self, other: Self) -> Self | 1.21.0 [src] |
Compares and returns the minimum of two values. Read more
Panics if the value in either RefCell
is currently borrowed.
This method tests for !=
.
Creates a RefCell<T>
, with the Default
value for T.
type Error = !
🔬 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)
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.
🔬 This is a nightly-only experimental API. (
try_from
#33417)
Immutably borrows from an owned value. Read more
Mutably borrows from an owned value. Read more
🔬 This is a nightly-only experimental API. (get_type_id
#27745)
this method will likely be replaced by an associated static
type Owned = T
Creates owned data from borrowed data, usually by cloning. Read more
🔬 This is a nightly-only experimental API. (toowned_clone_into
#41263)
recently added
Uses borrowed data to replace owned data, usually by cloning. Read more