neon::types::extract

Struct With

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pub struct With<F, O>(pub F)
where
    for<'cx> F: FnOnce(&mut Cx<'cx>) -> O;
Expand description

Wraps a closure that will be lazily evaluated when TryIntoJs::try_into_js is called.

Useful for executing arbitrary code on the main thread before returning from a function exported with neon::export.

§Example

use std::time::Instant;

#[neon::export(task)]
fn sum(nums: Vec<f64>) -> impl for<'cx> TryIntoJs<'cx> {
    let start = Instant::now();
    let sum = nums.into_iter().sum::<f64>();
    let log = format!("sum took {} ms", start.elapsed().as_millis());

    With(move |cx| -> NeonResult<_> {
        cx.global::<JsObject>("console")?
            .method(cx, "log")?
            .arg(&log)?
            .exec()?;

        Ok(sum)
    })
}

Tuple Fields§

§0: F

Trait Implementations§

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impl<'cx, F, O> TryIntoJs<'cx> for With<F, O>
where F: FnOnce(&mut Cx<'_>) -> O, O: TryIntoJs<'cx>,

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type Value = <O as TryIntoJs<'cx>>::Value

The type of JavaScript value that will be created
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fn try_into_js(self, cx: &mut Cx<'cx>) -> JsResult<'cx, Self::Value>

Convert self into a JavaScript value
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impl<'cx, F, O> TryIntoArguments<'cx> for With<F, O>
where F: FnOnce(&mut Cx<'_>) -> O, O: TryIntoArguments<'cx>,

Auto Trait Implementations§

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impl<F, O> Freeze for With<F, O>
where F: Freeze,

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impl<F, O> RefUnwindSafe for With<F, O>
where F: RefUnwindSafe,

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impl<F, O> Send for With<F, O>
where F: Send,

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impl<F, O> Sync for With<F, O>
where F: Sync,

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impl<F, O> Unpin for With<F, O>
where F: Unpin,

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impl<F, O> UnwindSafe for With<F, O>
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> 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<T> IntoEither for T

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fn into_either(self, into_left: bool) -> Either<Self, Self>

Converts self into a Left variant of Either<Self, Self> if into_left is true. Converts self into a Right variant of Either<Self, Self> otherwise. Read more
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fn into_either_with<F>(self, into_left: F) -> Either<Self, Self>
where F: FnOnce(&Self) -> bool,

Converts self into a Left variant of Either<Self, Self> if into_left(&self) returns true. Converts self into a Right variant of Either<Self, Self> otherwise. 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.