In some programming languages such as Oz, E, and AmbientTalk, it is possible to obtain a read-only view of a future, which allows reading its value when resolved, but does not permit resolving it: In Oz, the !! operator is used to obtain a read-only view.
在某些编程语言（如Oz\E和AmbientTalk）中 ，可以获得未来的只读视图 ，该视图允许在resolve后读取其值，但不允许resolve它： 在Oz语言中， !