Struct holochain::prelude::dependencies::kitsune_p2p_types::dependencies::lair_keystore_api::dependencies::once_cell::unsync::Lazy
source · pub struct Lazy<T, F = fn() -> T> { /* private fields */ }
Expand description
A value which is initialized on the first access.
Example
use once_cell::unsync::Lazy;
let lazy: Lazy<i32> = Lazy::new(|| {
println!("initializing");
92
});
println!("ready");
println!("{}", *lazy);
println!("{}", *lazy);
// Prints:
// ready
// initializing
// 92
// 92
Implementations
sourceimpl<T, F> Lazy<T, F>
impl<T, F> Lazy<T, F>
sourcepub const fn new(init: F) -> Lazy<T, F>
pub const fn new(init: F) -> Lazy<T, F>
Creates a new lazy value with the given initializing function.
Example
use once_cell::unsync::Lazy;
let hello = "Hello, World!".to_string();
let lazy = Lazy::new(|| hello.to_uppercase());
assert_eq!(&*lazy, "HELLO, WORLD!");
sourcepub fn into_value(this: Lazy<T, F>) -> Result<T, F>
pub fn into_value(this: Lazy<T, F>) -> Result<T, F>
Consumes this Lazy
returning the stored value.
Returns Ok(value)
if Lazy
is initialized and Err(f)
otherwise.
sourceimpl<T, F> Lazy<T, F>where
F: FnOnce() -> T,
impl<T, F> Lazy<T, F>where
F: FnOnce() -> T,
sourcepub fn force(this: &Lazy<T, F>) -> &T
pub fn force(this: &Lazy<T, F>) -> &T
Forces the evaluation of this lazy value and returns a reference to the result.
This is equivalent to the Deref
impl, but is explicit.
Example
use once_cell::unsync::Lazy;
let lazy = Lazy::new(|| 92);
assert_eq!(Lazy::force(&lazy), &92);
assert_eq!(&*lazy, &92);
sourcepub fn force_mut(this: &mut Lazy<T, F>) -> &mut T
pub fn force_mut(this: &mut Lazy<T, F>) -> &mut T
Forces the evaluation of this lazy value and returns a mutable reference to the result.
This is equivalent to the DerefMut
impl, but is explicit.
Example
use once_cell::unsync::Lazy;
let mut lazy = Lazy::new(|| 92);
assert_eq!(Lazy::force_mut(&mut lazy), &92);
assert_eq!(*lazy, 92);
sourcepub fn get(this: &Lazy<T, F>) -> Option<&T>
pub fn get(this: &Lazy<T, F>) -> Option<&T>
Gets the reference to the result of this lazy value if
it was initialized, otherwise returns None
.
Example
use once_cell::unsync::Lazy;
let lazy = Lazy::new(|| 92);
assert_eq!(Lazy::get(&lazy), None);
assert_eq!(&*lazy, &92);
assert_eq!(Lazy::get(&lazy), Some(&92));
sourcepub fn get_mut(this: &mut Lazy<T, F>) -> Option<&mut T>
pub fn get_mut(this: &mut Lazy<T, F>) -> Option<&mut T>
Gets the mutable reference to the result of this lazy value if
it was initialized, otherwise returns None
.
Example
use once_cell::unsync::Lazy;
let mut lazy = Lazy::new(|| 92);
assert_eq!(Lazy::get_mut(&mut lazy), None);
assert_eq!(*lazy, 92);
assert_eq!(Lazy::get_mut(&mut lazy), Some(&mut 92));
Trait Implementations
impl<T, F> RefUnwindSafe for Lazy<T, F>where
F: RefUnwindSafe,
OnceCell<T>: RefUnwindSafe,
Auto Trait Implementations
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,
Blanket Implementations
impl<T> Any for Twhere
T: Any + ?Sized,
impl<T> Any for Twhere
T: Any + ?Sized,
fn type_id_compat(&self) -> TypeId
fn type_id_compat(&self) -> TypeId
TODO: once 1.33.0 is the minimum supported compiler version, remove
Any::type_id_compat and use StdAny::type_id instead.
https://github.com/rust-lang/rust/issues/27745 Read more
impl<T> ArchivePointee for T
impl<T> ArchivePointee for T
type ArchivedMetadata = ()
type ArchivedMetadata = ()
The archived version of the pointer metadata for this type.
fn pointer_metadata(
_: &<T as ArchivePointee>::ArchivedMetadata
) -> <T as Pointee>::Metadata
fn pointer_metadata(
_: &<T as ArchivePointee>::ArchivedMetadata
) -> <T as Pointee>::Metadata
Converts some archived metadata to the pointer metadata for itself.
sourceimpl<T> BorrowMut<T> for Twhere
T: ?Sized,
impl<T> BorrowMut<T> for Twhere
T: ?Sized,
const: unstable · sourcefn borrow_mut(&mut self) -> &mut T
fn borrow_mut(&mut self) -> &mut T
Mutably borrows from an owned value. Read more
impl<F, W, T, D> Deserialize<With<T, W>, D> for Fwhere
W: DeserializeWith<F, T, D>,
D: Fallible + ?Sized,
F: ?Sized,
impl<F, W, T, D> Deserialize<With<T, W>, D> for Fwhere
W: DeserializeWith<F, T, D>,
D: Fallible + ?Sized,
F: ?Sized,
fn deserialize(
&self,
deserializer: &mut D
) -> Result<With<T, W>, <D as Fallible>::Error>
fn deserialize(
&self,
deserializer: &mut D
) -> Result<With<T, W>, <D as Fallible>::Error>
Deserializes using the given deserializer
impl<T> FutureExt for T
impl<T> FutureExt for T
fn with_context(self, otel_cx: Context) -> WithContext<Self> ⓘ
fn with_context(self, otel_cx: Context) -> WithContext<Self> ⓘ
fn with_current_context(self) -> WithContext<Self> ⓘ
fn with_current_context(self) -> WithContext<Self> ⓘ
sourceimpl<T> Instrument for T
impl<T> Instrument for T
sourcefn instrument(self, span: Span) -> Instrumented<Self> ⓘ
fn instrument(self, span: Span) -> Instrumented<Self> ⓘ
sourcefn in_current_span(self) -> Instrumented<Self> ⓘ
fn in_current_span(self) -> Instrumented<Self> ⓘ
sourceimpl<T> Instrument for T
impl<T> Instrument for T
sourcefn instrument(self, span: Span) -> Instrumented<Self> ⓘ
fn instrument(self, span: Span) -> Instrumented<Self> ⓘ
sourcefn in_current_span(self) -> Instrumented<Self> ⓘ
fn in_current_span(self) -> Instrumented<Self> ⓘ
impl<T> Pointable for T
impl<T> Pointable for T
impl<SS, SP> SupersetOf<SS> for SPwhere
SS: SubsetOf<SP>,
impl<SS, SP> SupersetOf<SS> for SPwhere
SS: SubsetOf<SP>,
fn to_subset(&self) -> Option<SS>
fn to_subset(&self) -> Option<SS>
The inverse inclusion map: attempts to construct
self
from the equivalent element of its
superset. Read morefn is_in_subset(&self) -> bool
fn is_in_subset(&self) -> bool
Checks if
self
is actually part of its subset T
(and can be converted to it).fn to_subset_unchecked(&self) -> SS
fn to_subset_unchecked(&self) -> SS
Use with care! Same as
self.to_subset
but without any property checks. Always succeeds.fn from_subset(element: &SS) -> SP
fn from_subset(element: &SS) -> SP
The inclusion map: converts
self
to the equivalent element of its superset.