Struct LocalKey

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

Available on crate feature napi-6 only.

A JavaScript thread-local container that owns its contents, similar to std::thread::LocalKey but tied to a JavaScript thread rather than a system thread.

Initialization and Destruction

Initialization is dynamically performed on the first call to one of the init methods of LocalKey, and values that implement Drop get destructed when the JavaScript thread exits, i.e. when a worker thread terminates or the main thread terminates on process exit.

Implementations

impl<T> LocalKey<T>

pub const fn new() -> Self

Creates a new local value. This method is const, so it can be assigned to static variables.

impl<T: Any + Send + 'static> LocalKey<T>

pub fn get<'cx, 'a, C>(&self, cx: &'a mut C) -> Option<&'cx T>

where C: Context<'cx>,

Gets the current value of the cell. Returns None if the cell has not yet been initialized.

pub fn get_or_init<'cx, 'a, C, F>(&self, cx: &'a mut C, f: F) -> &'cx T

where C: Context<'cx>, F: FnOnce() -> T,

Gets the current value of the cell, initializing it with the result of calling f if it has not yet been initialized.

pub fn get_or_try_init<'cx, 'a, C, E, F>( &self, cx: &'a mut C, f: F, ) -> Result<&'cx T, E>

where C: Context<'cx>, F: FnOnce(&mut C) -> Result<T, E>,

Gets the current value of the cell, initializing it with the result of calling f if it has not yet been initialized. Returns Err if the callback triggers a JavaScript exception.

Panics

During the execution of f, calling any methods on this LocalKey that attempt to initialize it will panic.

impl<T: Any + Send + Default + 'static> LocalKey<T>

pub fn get_or_init_default<'cx, 'a, C>(&self, cx: &'a mut C) -> &'cx T

where C: Context<'cx>,

Gets the current value of the cell, initializing it with the default value if it has not yet been initialized.

Trait Implementations

impl<T: Default> Default for LocalKey<T>

fn default() -> LocalKey<T>

Returns the “default value” for a type.