pub struct LazyCell<T, F = fn() -> T> { /* private fields */ }Expand description
A value which is initialized on the first access.
For a thread-safe version of this struct, see std::sync::LazyLock.
§Examples
use std::cell::LazyCell;
let lazy: LazyCell<i32> = LazyCell::new(|| {
    println!("initializing");
    92
});
println!("ready");
println!("{}", *lazy);
println!("{}", *lazy);
// Prints:
//   ready
//   initializing
//   92
//   92Implementations§
source§impl<T, F> LazyCell<T, F>where
    F: FnOnce() -> T,
 
impl<T, F> LazyCell<T, F>where
    F: FnOnce() -> T,
sourcepub fn into_inner(this: LazyCell<T, F>) -> Result<T, F>
 🔬This is a nightly-only experimental API. (lazy_cell_consume #125623)
pub fn into_inner(this: LazyCell<T, F>) -> Result<T, F>
lazy_cell_consume #125623)Consumes this LazyCell returning the stored value.
Returns Ok(value) if Lazy is initialized and Err(f) otherwise.
§Examples
#![feature(lazy_cell_consume)]
use std::cell::LazyCell;
let hello = "Hello, World!".to_string();
let lazy = LazyCell::new(|| hello.to_uppercase());
assert_eq!(&*lazy, "HELLO, WORLD!");
assert_eq!(LazyCell::into_inner(lazy).ok(), Some("HELLO, WORLD!".to_string()));Trait Implementations§
Auto Trait Implementations§
impl<T, F = fn() -> T> !Freeze for LazyCell<T, F>
impl<T, F = fn() -> T> !RefUnwindSafe for LazyCell<T, F>
impl<T, F> Send for LazyCell<T, F>
impl<T, F = fn() -> T> !Sync for LazyCell<T, F>
impl<T, F> Unpin for LazyCell<T, F>
impl<T, F> UnwindSafe for LazyCell<T, F>where
    F: UnwindSafe,
    T: UnwindSafe,
Blanket Implementations§
source§impl<T> BorrowMut<T> for Twhere
    T: ?Sized,
 
impl<T> BorrowMut<T> for Twhere
    T: ?Sized,
source§fn borrow_mut(&mut self) -> &mut T
 
fn borrow_mut(&mut self) -> &mut T
Mutably borrows from an owned value. Read more