deref
- (deref ref)
- (deref ref timeout-ms timeout-val)
Also reader macro: @ref/@agent/@var/@atom/@delay/@future/@promise. Within a transaction, returns the in-transaction-value of ref, else returns the most-recently-committed value of ref. When applied to a var, agent or atom, returns its current state. When applied to a delay, forces it if not already forced. When applied to a future, will block if computation not complete. When applied to a promise, will block until a value is delivered. The variant taking a timeout can be used for blocking references (futures and promises), and will return timeout-val if the timeout (in milliseconds) is reached before a value is available. See also - realized?.
© Rich Hickey. 保留所有权利。 Eclipse 公共许可证 1.0
3 Examples
user=> (def a (atom 0)) #'user/a user=> @a 0 user=> (deref a) 0 user=> (def b (ref 1)) #'user/b user=> @b 1 user=> (deref b) 1 user=> (def c (agent 2)) #'user/c user=> @c 2 user=> (deref c) 2 user=> (def d (future 3)) #'user/d user=> @d 3 user=> (deref d) 3
