Struct Lazy

pub struct Lazy<T> { /* private fields */ }

Lazy<T> is a lazily initialized synchronized holder type. You can think of it as a LazyTransform where the initial type doesn’t exist.

Implementations

impl<T> Lazy<T>

pub fn new() -> Lazy<T>

Construct a new, uninitialized Lazy<T>.

pub fn into_inner(self) -> Option<T>

Unwrap the contained value, returning Some if the Lazy<T> has been initialized or None if it has not.

impl<T> Lazy<T>

pub fn get_or_create<F>(&self, f: F) -> &T

where F: FnOnce() -> T,

Get a reference to the contained value, invoking f to create it if the Lazy<T> is uninitialized. It is guaranteed that if multiple calls to get_or_create race, only one will invoke its closure, and every call will receive a reference to the newly created value.

The value stored in the Lazy<T> is immutable after the closure returns it, so think carefully about what you want to put inside!

pub fn try_get_or_create<F, E>(&self, f: F) -> Result<&T, E>

where F: FnOnce() -> Result<T, E>,

Tries to get a reference to the contained value, invoking f to create it if the Lazy<T> is uninitialized. It is guaranteed that if multiple calls to get_or_create race, only one will successfully invoke its closure, and every call will receive a reference to the newly created value.

The value stored in the Lazy<T> is immutable after the closure succeeds and returns it, so think carefully about what you want to put inside!

Errors

Iff f returns a Result::Err, this error is returned verbatim.

pub fn get(&self) -> Option<&T>

Get a reference to the contained value, returning Some(ref) if the Lazy<T> has been initialized or None if it has not. It is guaranteed that if a reference is returned it is to the value inside the Lazy<T>.

Trait Implementations

impl<T: Clone> Clone for Lazy<T>

fn clone(&self) -> Lazy<T>

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<T> Debug for Lazy<T>

where T: Debug,

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<T> Default for Lazy<T>

fn default() -> Self

Returns the “default value” for a type.