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Discard

Struct Discard 

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pub struct Discard<F>(pub F);
Expand description

Timer is defined once, in hclient-core: the portable core needs it for timeouts and backoff. This is just a re-export.

Discard comes with it: Timer::Sleep is a named associated type, and a runtime whose native timer resolves to something other than () — as async_io::Timer does — needs the adapter to satisfy it. Re-exported here so a runtime crate does not have to depend on hclient-core directly just to name one wrapper. Adapts a future that resolves to something into one that resolves to (), for use as a Timer::Sleep.

This is not redundant, and it is not a mistake. Two of this project’s clocks have a native timer whose Output is not (): async_io::Timer resolves to the std::time::Instant at which it fired, and hclient-fetch’s SendJsFuture resolves to Result<JsValue, JsValue>. While Timer::sleep was an RPITIT both were discarded invisibly inside an async block; with a named associated type the discard has to be written down, and this is where it is written down once instead of twice.

F: Unpin rather than a pin projection: every timer this wraps is Unpin already, and this workspace forbids unsafe, so the safe projection is the only one available and the bound is honest about it.

Tuple Fields§

§0: F

Trait Implementations§

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impl<F> Clone for Discard<F>
where F: Clone,

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fn clone(&self) -> Discard<F>

Returns a duplicate of the value. Read more
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fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source. Read more
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impl<F> Copy for Discard<F>
where F: Copy,

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impl<F> Debug for Discard<F>
where F: Debug,

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fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter. Read more
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impl<F> Future for Discard<F>
where F: Future + Unpin,

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type Output = ()

The type of value produced on completion.
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fn poll(self: Pin<&mut Discard<F>>, cx: &mut Context<'_>) -> Poll<()>

Attempts to resolve the future to a final value, registering the current task for wakeup if the value is not yet available. Read more

Auto Trait Implementations§

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impl<F> Freeze for Discard<F>
where F: Freeze,

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impl<F> RefUnwindSafe for Discard<F>
where F: RefUnwindSafe,

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impl<F> Send for Discard<F>
where F: Send,

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impl<F> Sync for Discard<F>
where F: Sync,

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impl<F> Unpin for Discard<F>
where F: Unpin,

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impl<F> UnsafeUnpin for Discard<F>
where F: UnsafeUnpin,

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impl<F> UnwindSafe for Discard<F>
where F: UnwindSafe,

Blanket Implementations§

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impl<T> Any for T
where 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 T
where T: ?Sized,

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fn borrow(&self) -> &T

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

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

Mutably borrows from an owned value. Read more
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impl<T> CloneToUninit for T
where T: Clone,

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unsafe fn clone_to_uninit(&self, dest: *mut u8)

🔬This is a nightly-only experimental API. (clone_to_uninit)
Performs copy-assignment from self to dest. Read more
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T, U> Into<U> for T
where U: From<T>,

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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<F> IntoFuture for F
where F: Future,

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type Output = <F as Future>::Output

The output that the future will produce on completion.
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type IntoFuture = F

Which kind of future are we turning this into?
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fn into_future(self) -> <F as IntoFuture>::IntoFuture

Creates a future from a value. Read more
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impl<T> ToOwned for T
where T: Clone,

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type Owned = T

The resulting type after obtaining ownership.
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fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more
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fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. Read more
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impl<T, U> TryFrom<U> for T
where U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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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 T
where U: TryFrom<T>,

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

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.