Jacl Library Procedures - TclEvent manual page

  CLASS
    tcl.lang.TclEvent -- Subclass from this abstract base class to create event handlers.
  METHODS
    abstract int processEvent(int flags)
    synchronized final void sync()
  ARGUMENTS
  DESCRIPTION
    processEvent
    sync
  EQUIVALENT C FUNCTIONS
  SEE ALSO
  KEYWORDS

### CLASS

tcl.lang.TclEvent -- Subclass from this abstract base class to create event handlers.

### METHODS

abstract int processEvent(int flags)

synchronized final void sync()

### ARGUMENTS

int flags ()
  Same as flags passed to the doOneEvent method of the Notifier class.

### DESCRIPTION

The TclEvent class is used to schedule events to be processed in a Jacl Notifier. Usually, an event-driven Jacl application consists of one "Notifier Thread" and one or more "Event Detection Threads". When an Event Detection Thread detects an event, it puts an instance of TclEvent on the queue of the Notifier. Then, when the Notifier Thread is ready to process events (i.e., when the doOneEvent method of the Notifier class is invoked), it invokes the processEvent method of the TclEvent instances in the order they appear in the Notifier's event queue.

processEvent
  When processEvent is called, it should determine whether the event can be processed right away (possibly based on the settings of the flags parameter). If the event cannot be processed yet, this method returns 0, in which case the Notifier will leave the event in the event queue and defer its processing to some later time. Otherwise, this method should process the event and return 1, in which case the Notifier will remove the event from the event queue.

sync
  Usually, TclEvent instances are processed asynchronously. If synchronous processing is desired, an Event Detection Thread can call the sync method, which waits until the event is processed by the Notifier. The TclEvent must be in the event queue before its sync method can be invoked, otherwise a TclRuntimeError will be generated.

### EQUIVALENT C FUNCTIONS

Tcl_EventProc, Tcl_ServiceAll

### SEE ALSO

Notifier, Interp, TclRuntimeError, IdleHandler, TimerHandler

### KEYWORDS

event, event queue, thread, event sources, event detection

    Copyright © 1998 Sun Microsystems, Inc.
    Copyright © 1995-1997 Roger E. Critchlow Jr.