pub struct SingleUse<T>(_);
Expand description

A wrapper type for Command payloads that should only be used once.

This is useful if you have some resource that cannot be cloned, and you wish to send it to another widget.

Examples

use druid::{Command, Selector, SingleUse, Target};

struct CantClone(u8);

let selector = Selector::new("use-once");
let num = CantClone(42);
let command = selector.with(SingleUse::new(num));

let payload: &SingleUse<CantClone> = command.get_unchecked(selector);
if let Some(num) = payload.take() {
    // now you own the data
    assert_eq!(num.0, 42);
}

// subsequent calls will return `None`
assert!(payload.take().is_none());

Implementations§

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impl<T> SingleUse<T>where T: Any,

pub fn new(data: T) -> SingleUse<T>

Create a new single-use payload.

pub fn take(&self) -> Option<T>

Takes the value, leaving a None in its place.

Auto Trait Implementations§

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impl<T> RefUnwindSafe for SingleUse<T>

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impl<T> Send for SingleUse<T>where T: Send,

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impl<T> Sync for SingleUse<T>where T: Send,

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impl<T> Unpin for SingleUse<T>where T: Unpin,

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impl<T> UnwindSafe for SingleUse<T>

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impl<T> Any for Twhere T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for Twhere T: ?Sized,

const: unstable · source§

fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for Twhere T: ?Sized,

const: unstable · source§

fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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impl<T> From<T> for T

const: unstable · source§

fn from(t: T) -> T

Returns the argument unchanged.

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impl<T> Instrument for T

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fn instrument(self, span: Span) -> Instrumented<Self>

Instruments this type with the provided [Span], returning an Instrumented wrapper. Read more
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fn in_current_span(self) -> Instrumented<Self>

Instruments this type with the current Span, returning an Instrumented wrapper. Read more
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impl<T, U> Into<U> for Twhere U: From<T>,

const: unstable · source§

fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<T> Pointable for T

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const ALIGN: usize = mem::align_of::<T>()

The alignment of pointer.
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type Init = T

The type for initializers.
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unsafe fn init(init: <T as Pointable>::Init) -> usize

Initializes a with the given initializer. Read more
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unsafe fn deref<'a>(ptr: usize) -> &'a T

Dereferences the given pointer. Read more
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unsafe fn deref_mut<'a>(ptr: usize) -> &'a mut T

Mutably dereferences the given pointer. Read more
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unsafe fn drop(ptr: usize)

Drops the object pointed to by the given pointer. Read more
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impl<T> RoundFrom<T> for T

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fn round_from(x: T) -> T

Performs the conversion.
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impl<T, U> RoundInto<U> for Twhere U: RoundFrom<T>,

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fn round_into(self) -> U

Performs the conversion.
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impl<T> Same<T> for T

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type Output = T

Should always be Self
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impl<T, U> TryFrom<U> for Twhere U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
const: unstable · source§

fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for Twhere U: TryFrom<T>,

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type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
const: unstable · source§

fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.
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impl<V, T> VZip<V> for Twhere V: MultiLane<T>,

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fn vzip(self) -> V

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impl<T> WithSubscriber for T

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fn with_subscriber<S>(self, subscriber: S) -> WithDispatch<Self> where S: Into<Dispatch>,

Attaches the provided Subscriber to this type, returning a [WithDispatch] wrapper. Read more
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fn with_current_subscriber(self) -> WithDispatch<Self>

Attaches the current default Subscriber to this type, returning a [WithDispatch] wrapper. Read more