Programming Guide - Actian

Chapter 12: Managing Event QueuesThis section contains the following topics:Conceptual Background (see page 317)Event-based Programming (see page 318)OpenROAD uses event queues to manage the order in which events areprocessed. Event queues can apply to the entire application or to individualframes. This chapter discusses:• Event queues in the context of event-based programming and the threebasic event types:– Frame– Field– Menu• Interrupting event queues that are programmed in event blocks• Obtaining information about a current eventFor a discussion of writing event blocks, see Writing Scripts and Procedures(see page 67).Conceptual BackgroundAlthough the user perceives the application as an environment in which severaltasks can be performed concurrently, events in an OpenROAD application areexecuted one at a time. The sequential ordering of tasks is handled by theevent queue that is maintained for an entire application, as well as eventqueues for each frame.Managing Event Queues 317