Struct WeakListElement

Source

pub struct WeakListElement<T>where
    T: ?Sized,
{ /* private fields */ }

Expand description

An element that can be inserted into a weak list.

Each element can be attached to 0 or 1 list. Attaching it to a list automatically detaches itself from the previous list.

When this object is dropped, it detaches itself from its current list.

Implementations§

Source §

impl<T> WeakListElement<T>
where T: ?Sized,

Source

pub fn new(t: Weak<T>) -> Self

Creates a new list element.

This object holds a weak reference to the T. When this object is dropped, it automatically detaches itself from the list it is currently attached to.

Often, this object is directly contained in the T:

use std::rc::Rc;
use weak_lists::WeakListElement;

struct Client {
    element: WeakListElement<Client>,
}

let client = Rc::new_cyclic(|slf| Client {
    element: WeakListElement::new(slf.clone()),
});

Since only weak references are stored, this does not create any actual reference cycles.

Source

pub fn attach(&self, to: &WeakList<T>)

Attaches the list element to a list.

If this object was previously attached to a list, it is automatically detached from that list.

The list will only hold on a weak reference to this element and vice versa.

Any existing iterator over the list might or might not see this element, this is unspecified.

§Examples

use std::rc::Rc;
use weak_lists::{WeakList, WeakListElement};

struct Client {
    element: WeakListElement<Client>,
}

let clients1 = WeakList::default();

let client = Rc::new_cyclic(|slf| Client {
    element: WeakListElement::new(slf.clone()),
});

client.element.attach(&clients1);

assert!(clients1.iter().next().is_some());

let clients2 = WeakList::default();

client.element.attach(&clients2);

assert!(clients1.iter().next().is_none());
assert!(clients2.iter().next().is_some());

Source

pub fn detach(&self)

Detaches the element from its current list.

§Examples

use std::rc::Rc;
use weak_lists::{WeakList, WeakListElement};

struct Client {
    element: WeakListElement<Client>,
}

let clients = WeakList::default();

let client = Rc::new_cyclic(|slf| Client {
    element: WeakListElement::new(slf.clone()),
});

client.element.attach(&clients);

assert!(clients.iter().next().is_some());

client.element.detach();

assert!(clients.iter().next().is_none());