Owning Palette: Message Queue VIs (Actor Framework)
Requires: Base Development System
(Filename: Actor Framework.lvlib:Message Dequeuer.lvclass:Equals Not A Refnum.vi)
Checks whether a message dequeuer reference is equal to Not a Refnum. Unlike the Not a Number/Path/Refnum? function, this function does not check whether a non-zero reference still is valid. Refer to the detailed help for more information.
This function only checks whether Message Dequeuer is equal to Not a Refnum. It does not check whether Message Dequeuer still is valid because doing so can introduce a race condition into the application. It is possible for a refnum to become invalid after being declared valid but before a message is read from it.
|Message Dequeuer specifies a message dequeuer to check.|
|Not a refnum? returns TRUE if Message Dequeuer is equal to Not a Refnum, in which case you should not attempt to use this reference to read a message.|
This output returns FALSE in all other situations, including when Message Dequeuer is a non-zero refnum that has been released already. In these situations, send the message and then check for an error on that operation.