pub struct Lazy<T, F = fn() -> T> { /* fields omitted */ }
A value which is initialized on the first access.
#![feature(once_cell)]
use std::lazy::Lazy;
let lazy: Lazy<i32> = Lazy::new(|| {
println!("initializing");
92
});
println!("ready");
println!("{}", *lazy);
println!("{}", *lazy);
// Prints:
// ready
// initializing
// 92
// 92impl<T, F> Lazy<T, F>[src]
pub fn new(init: F) -> Lazy<T, F>[src]
Creates a new lazy value with the given initializing function.
#![feature(once_cell)] use std::lazy::Lazy; let hello = "Hello, World!".to_string(); let lazy = Lazy::new(|| hello.to_uppercase()); assert_eq!(&*lazy, "HELLO, WORLD!");
impl<T, F> Lazy<T, F> where
F: FnOnce() -> T, [src]
pub fn force(this: &Lazy<T, F>) -> &TⓘNotable traits for &'_ mut F
impl<'_, F> Future for &'_ mut F where
F: Unpin + Future + ?Sized,
type Output = <F as Future>::Output;
impl<'_, I> Iterator for &'_ mut I where
I: Iterator + ?Sized,
type Item = <I as Iterator>::Item;
impl<R: Read + ?Sized, '_> Read for &'_ mut R
impl<W: Write + ?Sized, '_> Write for &'_ mut W
[src]
Forces the evaluation of this lazy value and returns a reference to the result.
This is equivalent to the Deref impl, but is explicit.
#![feature(once_cell)] use std::lazy::Lazy; let lazy = Lazy::new(|| 92); assert_eq!(Lazy::force(&lazy), &92); assert_eq!(&*lazy, &92);
impl<T, F> Debug for Lazy<T, F> where
T: Debug, [src]
impl<T> Default for Lazy<T, fn() -> T> where
T: Default, [src]
fn default() -> Lazy<T, fn() -> T>[src]
Creates a new lazy value using Default as the initializing function.
impl<T, F> Deref for Lazy<T, F> where
F: FnOnce() -> T, [src]
type Target = TThe resulting type after dereferencing.
fn deref(&self) -> &TⓘNotable traits for &'_ mut F
impl<'_, F> Future for &'_ mut F where
F: Unpin + Future + ?Sized,
type Output = <F as Future>::Output;
impl<'_, I> Iterator for &'_ mut I where
I: Iterator + ?Sized,
type Item = <I as Iterator>::Item;
impl<R: Read + ?Sized, '_> Read for &'_ mut R
impl<W: Write + ?Sized, '_> Write for &'_ mut W
[src]
impl<T, F = fn() -> T> !RefUnwindSafe for Lazy<T, F>impl<T, F> Send for Lazy<T, F> where
F: Send,
T: Send, impl<T, F = fn() -> T> !Sync for Lazy<T, F>impl<T, F> Unpin for Lazy<T, F> where
F: Unpin,
T: Unpin, impl<T, F> UnwindSafe for Lazy<T, F> where
F: UnwindSafe,
T: UnwindSafe, impl<T> Any for T where
T: 'static + ?Sized, [src]
impl<T> Borrow<T> for T where
T: ?Sized, [src]
fn borrow(&self) -> &TⓘNotable traits for &'_ mut F
impl<'_, F> Future for &'_ mut F where
F: Unpin + Future + ?Sized,
type Output = <F as Future>::Output;
impl<'_, I> Iterator for &'_ mut I where
I: Iterator + ?Sized,
type Item = <I as Iterator>::Item;
impl<R: Read + ?Sized, '_> Read for &'_ mut R
impl<W: Write + ?Sized, '_> Write for &'_ mut W
[src]
impl<T> BorrowMut<T> for T where
T: ?Sized, [src]
fn borrow_mut(&mut self) -> &mut TⓘNotable traits for &'_ mut F
impl<'_, F> Future for &'_ mut F where
F: Unpin + Future + ?Sized,
type Output = <F as Future>::Output;
impl<'_, I> Iterator for &'_ mut I where
I: Iterator + ?Sized,
type Item = <I as Iterator>::Item;
impl<R: Read + ?Sized, '_> Read for &'_ mut R
impl<W: Write + ?Sized, '_> Write for &'_ mut W
[src]
impl<T> From<T> for T[src]
impl<T, U> Into<U> for T where
U: From<T>, [src]
impl<T, U> TryFrom<U> for T where
U: Into<T>, [src]
type Error = InfallibleThe type returned in the event of a conversion error.
fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>[src]
impl<T, U> TryInto<U> for T where
U: TryFrom<T>, [src]
© 2010 The Rust Project Developers
Licensed under the Apache License, Version 2.0 or the MIT license, at your option.
https://doc.rust-lang.org/std/lazy/struct.Lazy.html