Struct futures::future::Lazy

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#[must_use = "futures do nothing unless polled"]
pub struct Lazy<F, R: IntoFuture> { /* fields omitted */ }

[−] Expand description

A future which defers creation of the actual future until a callback is scheduled.

This is created by the lazy function.

Trait Implementations

impl<F, R> Future for Lazy<F, R> where
    F: FnOnce() -> R,
    R: IntoFuture, [+]

[+] Show hidden undocumented items

type Item = R::Item

The type of value that this future will resolved with if it is successful.

type Error = R::Error

The type of error that this future will resolve with if it fails in a normal fashion.

fn poll(&mut self) -> Poll<R::Item, R::Error>[−]

Query this future to see if its value has become available, registering interest if it is not.

fn wait(self) -> Result<Self::Item, Self::Error> where
    Self: Sized, [−]

Block the current thread until this future is resolved.

fn map<F, U>(self, f: F) -> Map<Self, F> where
    F: FnOnce(Self::Item) -> U,
    Self: Sized, [−]

Map this future's result to a different type, returning a new future of the resulting type.

fn map_err<F, E>(self, f: F) -> MapErr<Self, F> where
    F: FnOnce(Self::Error) -> E,
    Self: Sized, [−]

Map this future's error to a different error, returning a new future.

fn from_err<E: From<Self::Error>>(self) -> FromErr<Self, E> where
    Self: Sized, [−]

Map this future's error to any error implementing From for this future's Error, returning a new future.

fn then<F, B>(self, f: F) -> Then<Self, B, F> where
    F: FnOnce(Result<Self::Item, Self::Error>) -> B,
    B: IntoFuture,
    Self: Sized, [−]

Chain on a computation for when a future finished, passing the result of the future to the provided closure f.

fn and_then<F, B>(self, f: F) -> AndThen<Self, B, F> where
    F: FnOnce(Self::Item) -> B,
    B: IntoFuture<Error = Self::Error>,
    Self: Sized, [−]

Execute another future after this one has resolved successfully.

fn or_else<F, B>(self, f: F) -> OrElse<Self, B, F> where
    F: FnOnce(Self::Error) -> B,
    B: IntoFuture<Item = Self::Item>,
    Self: Sized, [−]

Execute another future if this one resolves with an error.

fn select<B>(self, other: B) -> Select<Self, B::Future> where
    B: IntoFuture<Item = Self::Item, Error = Self::Error>,
    Self: Sized, [−]

Waits for either one of two futures to complete.

fn select2<B>(self, other: B) -> Select2<Self, B::Future> where
    B: IntoFuture,
    Self: Sized, [−]

Waits for either one of two differently-typed futures to complete.

fn join<B>(self, other: B) -> Join<Self, B::Future> where
    B: IntoFuture<Error = Self::Error>,
    Self: Sized, [−]

Joins the result of two futures, waiting for them both to complete.

fn join3<B, C>(self, b: B, c: C) -> Join3<Self, B::Future, C::Future> where
    B: IntoFuture<Error = Self::Error>,
    C: IntoFuture<Error = Self::Error>,
    Self: Sized, [−]

Same as join, but with more futures.

fn join4<B, C, D>(
    self,
    b: B,
    c: C,
    d: D
) -> Join4<Self, B::Future, C::Future, D::Future> where
    B: IntoFuture<Error = Self::Error>,
    C: IntoFuture<Error = Self::Error>,
    D: IntoFuture<Error = Self::Error>,
    Self: Sized, [−]

Same as join, but with more futures.

fn join5<B, C, D, E>(
    self,
    b: B,
    c: C,
    d: D,
    e: E
) -> Join5<Self, B::Future, C::Future, D::Future, E::Future> where
    B: IntoFuture<Error = Self::Error>,
    C: IntoFuture<Error = Self::Error>,
    D: IntoFuture<Error = Self::Error>,
    E: IntoFuture<Error = Self::Error>,
    Self: Sized, [−]

Same as join, but with more futures.

fn into_stream(self) -> IntoStream<Self> where
    Self: Sized, [−]

Convert this future into a single element stream.

fn flatten(self) -> Flatten<Self> where
    Self::Item: IntoFuture,
    <Self::Item as IntoFuture>::Error: From<Self::Error>,
    Self: Sized, [−]

Flatten the execution of this future when the successful result of this future is itself another future.

fn flatten_stream(self) -> FlattenStream<Self> where
    Self::Item: Stream<Error = Self::Error>,
    Self: Sized, [−]

Flatten the execution of this future when the successful result of this future is a stream.

fn fuse(self) -> Fuse<Self> where
    Self: Sized, [−]

Fuse a future such that poll will never again be called once it has completed.

fn inspect<F>(self, f: F) -> Inspect<Self, F> where
    F: FnOnce(&Self::Item),
    Self: Sized, [−]

Do something with the item of a future, passing it on.

fn catch_unwind(self) -> CatchUnwind<Self> where
    Self: Sized + UnwindSafe, [−]

Catches unwinding panics while polling the future.

fn shared(self) -> Shared<Self> where
    Self: Sized, [−]

Create a cloneable handle to this future where all handles will resolve to the same result.

impl<F: Debug, R: Debug + IntoFuture> Debug for Lazy<F, R> where
    R::Future: Debug, [+]

[+] Show hidden undocumented items

fn fmt(&self, f: &mut Formatter) -> Result[−]

Formats the value using the given formatter.