pub struct LocalKey<T> { /* fields omitted */ }
A key for local data stored in a coroutine.
This type is generated by the coroutine_local!
macro and performs very
similarly to the thread_local!
macro and std::thread::LocalKey
types.
Data associated with a LocalKey<T>
is stored inside of a coroutine,
and the data is destroyed when the coroutine is completed.
coroutine-local data requires the 'static
bound to ensure it lives long
enough. When a key is accessed for the first time the coroutine's data is
initialized with the provided initialization expression to the macro.
Access this coroutine-local key, running the provided closure with a
reference to the value.
This function will access this coroutine-local key to retrieve the data
associated with the current coroutine and this key. If this is the first
time this key has been accessed on this coroutine, then the key will be
initialized with the initialization expression provided at the time the
coroutine_local!
macro was called.
The provided closure will be provided a shared reference to the
underlying data associated with this coroutine-local-key. The data itself
is stored inside of the current coroutine.
if it's not accessed in a coroutine context, it will use the thread local
storage as a backend, so it's safe to use it in thread context
This function can possibly panic for a number of reasons:
- If the initialization expression is run and it panics
- If the closure provided panics
🔬 This is a nightly-only experimental API. (try_from
)
The type returned in the event of a conversion error.
🔬 This is a nightly-only experimental API. (try_from
)
Immutably borrows from an owned value. Read more
Mutably borrows from an owned value. Read more
🔬 This is a nightly-only experimental API. (try_from
)
The type returned in the event of a conversion error.
🔬 This is a nightly-only experimental API. (try_from
)
🔬 This is a nightly-only experimental API. (get_type_id
)
this method will likely be replaced by an associated static