Struct core::cell::RefCell
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[src]
pub struct RefCell<T: ?Sized> {
borrow: Cell<BorrowFlag>,
value: UnsafeCell<T>,
}A mutable memory location with dynamically checked borrow rules
See the module-level documentation for more.
Fields
borrow | |
value |
Methods
impl<T> RefCell<T>
const fn new(value: T) -> RefCell<T>
Creates a new RefCell containing value.
Examples
fn main() { use std::cell::RefCell; let c = RefCell::new(5); }use std::cell::RefCell; let c = RefCell::new(5);
fn into_inner(self) -> T
Consumes the RefCell, returning the wrapped value.
Examples
fn main() { use std::cell::RefCell; let c = RefCell::new(5); let five = c.into_inner(); }use std::cell::RefCell; let c = RefCell::new(5); let five = c.into_inner();
impl<T: ?Sized> RefCell<T>
fn borrow_state(&self) -> BorrowState
borrow_state #27733)Query the current state of this RefCell
The returned value can be dispatched on to determine if a call to
borrow or borrow_mut would succeed.
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.
Examples
fn main() { use std::cell::RefCell; let c = RefCell::new(5); let borrowed_five = c.borrow(); let borrowed_five2 = c.borrow(); }use std::cell::RefCell; let c = RefCell::new(5); let borrowed_five = c.borrow(); let borrowed_five2 = c.borrow();
An example of panic:
fn main() { 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()); }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 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.
Examples
fn main() { use std::cell::RefCell; let c = RefCell::new(5); *c.borrow_mut() = 7; assert_eq!(*c.borrow(), 7); }use std::cell::RefCell; let c = RefCell::new(5); *c.borrow_mut() = 7; assert_eq!(*c.borrow(), 7);
An example of panic:
fn main() { 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()); }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());
unsafe fn as_unsafe_cell(&self) -> &UnsafeCell<T>
as_unsafe_cell #27708)Returns a reference to the underlying UnsafeCell.
This can be used to circumvent RefCell's safety checks.
This function is unsafe because UnsafeCell's field is public.