1.0.0[−][src]Struct core::cell::RefCell
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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pub const fn new(value: T) -> RefCell<T>
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Creates a new RefCell
containing value
.
Examples
use std::cell::RefCell; let c = RefCell::new(5);Run
pub fn into_inner(self) -> T
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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
pub fn replace(&self, t: T) -> T
1.24.0[src]
Replaces the wrapped value with a new one, returning the old value, without deinitializing either one.
This function corresponds to std::mem::replace
.
Panics
Panics if the value is currently borrowed.
Examples
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
pub fn replace_with<F: FnOnce(&mut T) -> T>(&self, f: F) -> T
1.35.0[src]
Replaces the wrapped value with a new one computed from f
, returning
the old value, without deinitializing either one.
Panics
Panics if the value is currently borrowed.
Examples
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
pub fn swap(&self, other: &Self)
1.24.0[src]
Swaps the wrapped value of self
with the wrapped value of other
,
without deinitializing either one.
This function corresponds to std::mem::swap
.
Panics
Panics if the value in either RefCell
is currently borrowed.
Examples
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
impl<T: ?Sized> RefCell<T>
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pub fn borrow(&self) -> Ref<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
pub fn try_borrow(&self) -> Result<Ref<T>, BorrowError>
1.13.0[src]
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
pub fn borrow_mut(&self) -> RefMut<T>
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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
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
pub fn try_borrow_mut(&self) -> Result<RefMut<T>, BorrowMutError>
1.13.0[src]
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
.
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
pub fn as_ptr(&self) -> *mut T
1.12.0[src]
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
pub fn get_mut(&mut self) -> &mut T
1.11.0[src]
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
pub unsafe fn try_borrow_unguarded(&self) -> Result<&T, BorrowError>
1.37.0[src]
Immutably borrows the wrapped value, returning an error if the value is currently mutably borrowed.
Safety
Unlike RefCell::borrow
, this method is unsafe because it does not
return a Ref
, thus leaving the borrow flag untouched. Mutably
borrowing the RefCell
while the reference returned by this method
is alive is undefined behaviour.
Examples
use std::cell::RefCell; let c = RefCell::new(5); { let m = c.borrow_mut(); assert!(unsafe { c.try_borrow_unguarded() }.is_err()); } { let m = c.borrow(); assert!(unsafe { c.try_borrow_unguarded() }.is_ok()); }Run
Trait Implementations
impl<T: ?Sized> Send for RefCell<T> where
T: Send,
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T: Send,
impl<T: ?Sized> !Sync 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 + PartialEq> PartialEq<RefCell<T>> for RefCell<T>
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fn eq(&self, other: &RefCell<T>) -> bool
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Panics
Panics if the value in either RefCell
is currently borrowed.
#[must_use]
fn ne(&self, other: &Rhs) -> bool
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impl<T: ?Sized + Eq> Eq for RefCell<T>
1.2.0[src]
impl<T: ?Sized + Ord> Ord for RefCell<T>
1.10.0[src]
fn cmp(&self, other: &RefCell<T>) -> Ordering
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Panics
Panics if the value in either RefCell
is currently borrowed.
fn max(self, other: Self) -> Self where
Self: Sized,
1.21.0[src]
Self: Sized,
fn min(self, other: Self) -> Self where
Self: Sized,
1.21.0[src]
Self: Sized,
fn clamp(self, min: Self, max: Self) -> Self where
Self: Sized,
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Self: Sized,
impl<T: ?Sized + PartialOrd> PartialOrd<RefCell<T>> for RefCell<T>
1.10.0[src]
fn partial_cmp(&self, other: &RefCell<T>) -> Option<Ordering>
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Panics
Panics if the value in either RefCell
is currently borrowed.
fn lt(&self, other: &RefCell<T>) -> bool
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Panics
Panics if the value in either RefCell
is currently borrowed.
fn le(&self, other: &RefCell<T>) -> bool
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Panics
Panics if the value in either RefCell
is currently borrowed.
fn gt(&self, other: &RefCell<T>) -> bool
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Panics
Panics if the value in either RefCell
is currently borrowed.
fn ge(&self, other: &RefCell<T>) -> bool
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Panics
Panics if the value in either RefCell
is currently borrowed.
impl<T: Clone> Clone for RefCell<T>
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fn clone(&self) -> RefCell<T>
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Panics
Panics if the value is currently mutably borrowed.
fn clone_from(&mut self, source: &Self)
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impl<T: Default> Default for RefCell<T>
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impl<T> From<T> for RefCell<T>
1.12.0[src]
impl<T: ?Sized + Debug> Debug for RefCell<T>
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Auto Trait Implementations
Blanket Implementations
impl<T, U> Into<U> for T where
U: From<T>,
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U: From<T>,
impl<T> From<T> for T
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impl<T, U> TryInto<U> for T where
U: TryFrom<T>,
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U: TryFrom<T>,
type Error = <U as TryFrom<T>>::Error
The type returned in the event of a conversion error.
fn try_into(Self) -> Result<U, <U as TryFrom<T>>::Error>
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impl<T, U> TryFrom<U> for T where
U: Into<T>,
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U: Into<T>,
type Error = Infallible
The type returned in the event of a conversion error.
fn try_from(U) -> Result<T, <T as TryFrom<U>>::Error>
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impl<T> Borrow<T> for T where
T: ?Sized,
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T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
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T: ?Sized,
fn borrow_mut(&mut Self) -> &mut T
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impl<T> Any for T where
T: 'static + ?Sized,
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T: 'static + ?Sized,