Message Dequeuer:Equals Not A Refnum

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.

Details  

	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.

Message Dequeuer:Equals Not A Refnum Details

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.