Type Definition tokenlock::UnsyncSingletonTokenRef [−][src]
type UnsyncSingletonTokenRef<'a, Tag> = SingletonTokenRef<'a, Tag, UnsyncVariant>;
Zero-sized logical equivalent of &'a
UnsyncSingletonToken
<Tag>
. The
!Sync
variant of SingletonTokenRef
.
Examples
struct MyTag; impl_singleton_token_factory!(MyTag); let token = UnsyncSingletonToken::<MyTag>::new().unwrap(); let lock = UnsyncTokenLock::new(token.id(), 1); // `UnsyncSingletonTokenRef` is zero-sized (unlike `&UnsyncSingletonToken`), so there is // no runtime overhead involved with passing `UnsyncSingletonTokenRef`. access_lock(token.borrow(), &lock); fn access_lock( token: UnsyncSingletonTokenRef<'_, MyTag>, lock: &UnsyncTokenLock<u32, SingletonTokenId<MyTag>>, ) { assert_eq!(*lock.read(&*token), 1); }
UnsyncSingletonTokenRef
does not allow mutable borrow:
ⓘ
let token_ref: UnsyncSingletonTokenRef<MyTag> = token.borrow(); // compile error: `UnsyncSingletonTokenRef` does not implement `DerefMut` *lock.write(&mut *token_ref) = 4;
UnsyncSingletonTokenRef
is not Send
-able because
UnsyncSingletonToken
is not Sync
:
ⓘ
let token: &'static UnsyncSingletonTokenGuard<MyTag> = Box::leak(Box::new(UnsyncSingletonToken::<MyTag>::new().unwrap())); let token_ref: UnsyncSingletonTokenRef<MyTag> = token.borrow(); // compile error: `UnsyncSingletonTokenRef` is not `Send` std::thread::spawn(move || { let _token_ref = token_ref; });