Struct std::thread::ScopedKey

pub struct ScopedKey<T: 'static> {
    // some fields omitted
}

Deprecated since 1.8.0

: hasn't proven itself over LocalKey

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.

Methods

impl<T> ScopedKey<T>

fn set<R, F>(&'static self, t: &T, cb: F) -> R where F: FnOnce() -> R

Deprecated since 1.8.0

: hasn't proven itself over LocalKey

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

#![feature(scoped_tls)] fn main() { 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); }); }

#![feature(scoped_tls)]

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);
});

fn with<R, F>(&'static self, cb: F) -> R where F: FnOnce(&T) -> R

Deprecated since 1.8.0

: hasn't proven itself over LocalKey

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

#![feature(scoped_tls)] fn main() { scoped_thread_local!(static FOO: u32); FOO.with(|slot| { // work with `slot` }); }

#![feature(scoped_tls)]

scoped_thread_local!(static FOO: u32);

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

fn is_set(&'static self) -> bool

Deprecated since 1.8.0

: hasn't proven itself over LocalKey

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