pub trait Pointable {
    type Init;

    const ALIGN: usize;

    unsafe fn init(init: Self::Init) -> usize;
    unsafe fn deref<'a>(ptr: usize) -> &'a Self;
    unsafe fn deref_mut<'a>(ptr: usize) -> &'a mut Self;
    unsafe fn drop(ptr: usize);
Expand description

Types that are pointed to by a single word.

In concurrent programming, it is necessary to represent an object within a word because atomic operations (e.g., reads, writes, read-modify-writes) support only single words. This trait qualifies such types that are pointed to by a single word.

The trait generalizes Box<T> for a sized type T. In a box, an object of type T is allocated in heap and it is owned by a single-word pointer. This trait is also implemented for [MaybeUninit<T>] by storing its size along with its elements and pointing to the pair of array size and elements.

Pointers to Pointable types can be stored in Atomic, Owned, and Shared. In particular, Crossbeam supports dynamically sized slices as follows.

use std::mem::MaybeUninit;
use crossbeam_epoch::Owned;

let o = Owned::<[MaybeUninit<i32>]>::init(10); // allocating [i32; 10]

Required Associated Types

The type for initializers.

Required Associated Constants

The alignment of pointer.

Required Methods

Initializes a with the given initializer.


The result should be a multiple of ALIGN.

Dereferences the given pointer.


Mutably dereferences the given pointer.


Drops the object pointed to by the given pointer.


Implementations on Foreign Types