Trait WeakVar

pub trait WeakVar<T: VarValue>: AnyWeakVar + Clone {
    type Upgrade: Var<T>;

    // Required method
    fn upgrade(&self) -> Option<Self::Upgrade>;

    // Provided method
    fn boxed(self) -> BoxedWeakVar<T>
       where Self: Sized { ... }
}

Represents a weak reference to a Var<T>.

Required Associated Types

type Upgrade: Var<T>

Output of WeakVar::upgrade.

Required Methods

fn upgrade(&self) -> Option<Self::Upgrade>

Upgrade to a strong BoxedVar<T> clone.

Returns None if the strong_count is zero.

Provided Methods

fn boxed(self) -> BoxedWeakVar<T>

where Self: Sized,

Gets the weak reference a as BoxedWeakVar<T>, does not double box.

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementors

impl<I: VarValue, O: VarValue, S: WeakVar<I>> WeakVar<O> for WeakMapRef<I, O, S>

type Upgrade = MapRef<I, O, <S as WeakVar<I>>::Upgrade>

impl<I: VarValue, O: VarValue, S: WeakVar<I>> WeakVar<O> for WeakMapRefBidi<I, O, S>

type Upgrade = MapRefBidi<I, O, <S as WeakVar<I>>::Upgrade>

impl<T, V> WeakVar<T> for WeakFlatMapVar<T, V>

where T: VarValue, V: Var<T>,

type Upgrade = ArcFlatMapVar<T, V>

impl<T: VarValue> WeakVar<T> for WeakArcVar<T>

type Upgrade = ArcVar<T>

impl<T: VarValue> WeakVar<T> for WeakContextualizedVar<T>

type Upgrade = ContextualizedVar<T>

impl<T: VarValue> WeakVar<T> for WeakMergeVar<T>

type Upgrade = ArcMergeVar<T>

impl<T: VarValue> WeakVar<T> for WeakWhenVar<T>

type Upgrade = ArcWhenVar<T>

impl<T: VarValue> WeakVar<T> for BoxedWeakVar<T>

type Upgrade = Box<dyn VarBoxed<T>>

impl<T: VarValue, S: Var<T>> WeakVar<T> for WeakCowVar<T, S>

type Upgrade = ArcCowVar<T, S>

impl<T: VarValue, V: WeakVar<T>> WeakVar<T> for WeakReadOnlyVar<T, V>

type Upgrade = <<V as WeakVar<T>>::Upgrade as Var<T>>::ReadOnly