Trait LocalKeyExt

pub trait LocalKeyExt<T> {
    // Required methods
    fn with_borrow<F, R>(&'static self, f: F) -> R
       where F: FnOnce(&T) -> R;
    fn with_borrow_mut<F, R>(&'static self, f: F) -> R
       where F: FnOnce(&mut T) -> R;
    fn set(&'static self, value: T);
    fn take(&'static self) -> T
       where T: Default;
    fn replace(&'static self, value: T) -> T;
}

Required Methods

fn with_borrow<F, R>(&'static self, f: F) -> R

where F: FnOnce(&T) -> R,

Acquires a reference to the contained value.

This will lazily initialize the value if this thread has not referenced this key yet.

Panics

Panics if the value is currently mutably borrowed.

Panics if the key currently has its destructor running, and it may panic if the destructor has previously been run for this thread.

Example

use interrupt_ref_cell::{InterruptRefCell, LocalKeyExt};

thread_local! {
    static X: InterruptRefCell<Vec<i32>> = InterruptRefCell::new(Vec::new());
}

X.with_borrow(|v| assert!(v.is_empty()));

fn with_borrow_mut<F, R>(&'static self, f: F) -> R

where F: FnOnce(&mut T) -> R,

Acquires a mutable reference to the contained value.

This will lazily initialize the value if this thread has not referenced this key yet.

Panics

Panics if the value is currently borrowed.

Panics if the key currently has its destructor running, and it may panic if the destructor has previously been run for this thread.

Example

use interrupt_ref_cell::{InterruptRefCell, LocalKeyExt};

thread_local! {
    static X: InterruptRefCell<Vec<i32>> = InterruptRefCell::new(Vec::new());
}

X.with_borrow_mut(|v| v.push(1));

X.with_borrow(|v| assert_eq!(*v, vec![1]));

fn set(&'static self, value: T)

Sets the contained value.

This will run the lazy initializer.

Unlike LocalKey<RefCell<T>>::set, this method does run the lazy initializer of the thread local. The required API to avoid that is not not public.

Panics

Panics if the value is currently borrowed.

Panics if the key currently has its destructor running, and it may panic if the destructor has previously been run for this thread.

Examples

use interrupt_ref_cell::{InterruptRefCell, LocalKeyExt};

thread_local! {
    static X: InterruptRefCell<Vec<i32>> = InterruptRefCell::new(Vec::new());
}

// Calling X.with() here would result in a panic.

X.set(vec![1, 2, 3]); // But X.set() is fine, as it skips the initializer above.

X.with_borrow(|v| assert_eq!(*v, vec![1, 2, 3]));

fn take(&'static self) -> T

where T: Default,

Takes the contained value, leaving Default::default() in its place.

This will lazily initialize the value if this thread has not referenced this key yet.

Panics

Panics if the value is currently borrowed.

Panics if the key currently has its destructor running, and it may panic if the destructor has previously been run for this thread.

Examples

use interrupt_ref_cell::{InterruptRefCell, LocalKeyExt};

thread_local! {
    static X: InterruptRefCell<Vec<i32>> = InterruptRefCell::new(Vec::new());
}

X.with_borrow_mut(|v| v.push(1));

let a = X.take();

assert_eq!(a, vec![1]);

X.with_borrow(|v| assert!(v.is_empty()));

fn replace(&'static self, value: T) -> T

Replaces the contained value, returning the old value.

Panics

Panics if the value is currently borrowed.

Panics if the key currently has its destructor running, and it may panic if the destructor has previously been run for this thread.

Examples

use interrupt_ref_cell::{InterruptRefCell, LocalKeyExt};

thread_local! {
    static X: InterruptRefCell<Vec<i32>> = InterruptRefCell::new(Vec::new());
}

let prev = X.replace(vec![1, 2, 3]);
assert!(prev.is_empty());

X.with_borrow(|v| assert_eq!(*v, vec![1, 2, 3]));

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementations on Foreign Types

impl<T: 'static> LocalKeyExt<T> for LocalKey<InterruptRefCell<T>>

fn with_borrow<F, R>(&'static self, f: F) -> R

where F: FnOnce(&T) -> R,

fn with_borrow_mut<F, R>(&'static self, f: F) -> R

where F: FnOnce(&mut T) -> R,

fn set(&'static self, value: T)

fn take(&'static self) -> T

where T: Default,

fn replace(&'static self, value: T) -> T

Implementors