Trait WeakElement 

pub trait WeakElement {
    type Strong;

    // Required methods
    fn new(view: &Self::Strong) -> Self;
    fn view(&self) -> Option<Self::Strong>;

    // Provided methods
    fn is_expired(&self) -> bool { ... }
    fn clone(view: &Self::Strong) -> Self::Strong
       where Self: Sized { ... }
}

Interface for elements that can be stored in weak hash tables.

This trait applies to the weak version of a reference-counted pointer; it can be used to convert a weak pointer into a strong pointer and back. For example, the impl for std::rc::Weak<T> defines the Strong associated type as std::rc::Rc<T>. Then method new can be used to downgrade an Rc<T> to a Weak<T>, and method view can be used to upgrade a Weak<T> into an Rc<T>, if it’s still alive. If we think of the weak pointer as what is stored, then the strong pointer is a temporary view of it.

Required Associated Types

type Strong

The type at which a weak element can be viewed.

For example, for std::rc::Weak<T>, this will be std::rc::Rc<T>.

Required Methods

fn new(view: &Self::Strong) -> Self

Constructs a weak pointer from a strong pointer.

This is usually implemented by a downgrade method.

fn view(&self) -> Option<Self::Strong>

Acquires a strong pointer from a weak pointer.

This is usually implemented by an upgrade method.

Provided Methods

fn is_expired(&self) -> bool

Is the given weak element expired?

The default implemention checks whether a strong pointer can be obtained via view.

fn clone(view: &Self::Strong) -> Self::Strong

where Self: Sized,

Clones a strong pointer.

The default implementation uses new and view; you should override it.

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementations on Foreign Types

impl<T: ?Sized> WeakElement for Weak<T>

type Strong = Rc<T>

fn new(view: &Self::Strong) -> Self

fn view(&self) -> Option<Self::Strong>

fn clone(view: &Self::Strong) -> Self::Strong

impl<T: ?Sized> WeakElement for Weak<T>

type Strong = Arc<T>

fn new(view: &Self::Strong) -> Self

fn view(&self) -> Option<Self::Strong>

fn clone(view: &Self::Strong) -> Self::Strong

Implementors