Struct scoped_tls_hkt::ScopedKey

pub struct ScopedKey<T: ?Sized + 'static> { /* private fields */ }

Type representing a thread local storage key corresponding to a reference to the type parameter T.

Keys are statically allocated and can contain a reference to an instance of type T scoped to a particular lifetime. Keys provides two methods, set and with, both of which currently use closures to control the scope of their contents.

Implementations

impl<T: ?Sized + 'static> ScopedKey<T>

pub fn set<F, R>(&'static self, t: &T, f: F) -> Rwhere F: FnOnce() -> R,

Inserts a value into this scoped thread local storage slot for a duration of a closure.

While cb is running, the value t will be returned by get unless this function is called recursively inside of cb.

Upon return, this function will restore the previous value, if any was available.

Examples

use scoped_tls_hkt::scoped_thread_local;

scoped_thread_local!(static FOO: u32);

FOO.set(&100, || {
    let val = FOO.with(|v| *v);
    assert_eq!(val, 100);

    // set can be called recursively
    FOO.set(&101, || {
        // ...
    });

    // Recursive calls restore the previous value.
    let val = FOO.with(|v| *v);
    assert_eq!(val, 100);
});

pub fn with<F, R>(&'static self, f: F) -> Rwhere F: FnOnce(&T) -> R,

Gets a value out of this scoped variable.

This function takes a closure which receives the value of this variable.

Panics

This function will panic if set has not previously been called.

Examples

use scoped_tls_hkt::scoped_thread_local;

scoped_thread_local!(static FOO: u32);

FOO.with(|slot| {
    // work with `slot`
});

pub fn is_set(&'static self) -> bool

Test whether this TLS key has been set for the current thread.

Trait Implementations

impl<T: ?Sized + 'static> Sync for ScopedKey<T>