Struct core::cell::UnsafeCell
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pub struct UnsafeCell<T: ?Sized> {
value: T,
}The core primitive for interior mutability in Rust.
UnsafeCell<T> is a type that wraps some T and indicates unsafe interior operations on the
wrapped type. Types with an UnsafeCell<T> field are considered to have an 'unsafe interior'.
The UnsafeCell<T> type is the only legal way to obtain aliasable data that is considered
mutable. In general, transmuting an &T type into an &mut T is considered undefined behavior.
Types like Cell<T> and RefCell<T> use this type to wrap their internal data.
Examples
fn main() { use std::cell::UnsafeCell; use std::marker::Sync; #[allow(dead_code)] struct NotThreadSafe<T> { value: UnsafeCell<T>, } unsafe impl<T> Sync for NotThreadSafe<T> {} }use std::cell::UnsafeCell; use std::marker::Sync; struct NotThreadSafe<T> { value: UnsafeCell<T>, } unsafe impl<T> Sync for NotThreadSafe<T> {}
Fields
value |
Methods
impl<T> UnsafeCell<T>
const fn new(value: T) -> UnsafeCell<T>
Constructs a new instance of UnsafeCell which will wrap the specified
value.
All access to the inner value through methods is unsafe.
Examples
fn main() { use std::cell::UnsafeCell; let uc = UnsafeCell::new(5); }use std::cell::UnsafeCell; let uc = UnsafeCell::new(5);
unsafe fn into_inner(self) -> T
Unwraps the value.
Safety
This function is unsafe because this thread or another thread may currently be inspecting the inner value.
Examples
fn main() { use std::cell::UnsafeCell; let uc = UnsafeCell::new(5); let five = unsafe { uc.into_inner() }; }use std::cell::UnsafeCell; let uc = UnsafeCell::new(5); let five = unsafe { uc.into_inner() };
impl<T: ?Sized> UnsafeCell<T>
fn get(&self) -> *mut T
Gets a mutable pointer to the wrapped value.
Examples
fn main() { use std::cell::UnsafeCell; let uc = UnsafeCell::new(5); let five = uc.get(); }use std::cell::UnsafeCell; let uc = UnsafeCell::new(5); let five = uc.get();