Struct scoped_tls::ScopedKey
source · pub struct ScopedKey<T> { /* private fields */ }
Expand description
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§
source§impl<T> ScopedKey<T>
impl<T> ScopedKey<T>
sourcepub fn set<F, R>(&'static self, t: &T, f: F) -> Rwhere
F: FnOnce() -> R,
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 f
is running, the value t
will be returned by get
unless
this function is called recursively inside of f
.
Upon return, this function will restore the previous value, if any was available.
§Examples
#[macro_use]
extern crate 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);
});
sourcepub fn with<F, R>(&'static self, f: F) -> R
pub fn with<F, R>(&'static self, f: F) -> 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
#[macro_use]
extern crate scoped_tls;
scoped_thread_local!(static FOO: u32);
FOO.with(|slot| {
// work with `slot`
});