NAME

       Tcl_CreateTimerHandler, Tcl_DeleteTimerHandler - call a procedure at a given time

SYNOPSIS

       #include <tcl.h>

       Tcl_TimerToken
       Tcl_CreateTimerHandler(milliseconds, proc, clientData)

       Tcl_DeleteTimerHandler(token)

ARGUMENTS

       int milliseconds (in)                     How many milliseconds to wait before invoking proc.

       Tcl_TimerProc *proc (in)                  Procedure to invoke after milliseconds have elapsed.

       ClientData clientData (in)                Arbitrary one-word value to pass to proc.

       Tcl_TimerToken token (in)                 Token  for  previously  created timer handler (the return value
                                                 from some previous call to Tcl_CreateTimerHandler).
________________________________________________________________________________________________________________

DESCRIPTION

       Tcl_CreateTimerHandler arranges for proc to be invoked at a time milliseconds milliseconds in the future.
       The callback to proc will be made by Tcl_DoOneEvent, so Tcl_CreateTimerHandler is only useful in programs
       that dispatch events through Tcl_DoOneEvent or through Tcl commands such as vwait.  The call to proc  may
       not  be made at the exact time given by milliseconds:  it will be made at the next opportunity after that
       time.  For example, if Tcl_DoOneEvent is not called until long after the time has elapsed,  or  if  there
       are other pending events to process before the call to proc, then the call to proc will be delayed.

       Proc should have arguments and return value that match the type Tcl_TimerProc:

              typedef void Tcl_TimerProc(
                      ClientData clientData);

       The  clientData  parameter  to  proc is a copy of the clientData argument given to Tcl_CreateTimerHandler
       when the callback was created.  Typically, clientData points to a data structure containing  application-
       specific information about what to do in proc.

       Tcl_DeleteTimerHandler  may  be  called  to  delete  a  previously created timer handler.  It deletes the
       handler indicated by token so that no call to proc will be made;  if that handler no longer exists  (e.g.
       because  the  time  period has already elapsed and proc has been invoked then Tcl_DeleteTimerHandler does
       nothing.  The tokens returned by Tcl_CreateTimerHandler never have a value of NULL, so if NULL is  passed
       to Tcl_DeleteTimerHandler then the procedure does nothing.

SEE ALSO

       after(3tcl), Tcl_CreateFileHandler(3tcl), Tcl_DoWhenIdle(3tcl)

KEYWORDS

       callback, clock, handler, timer

Tcl                                                    7.5                          Tcl_CreateTimerHandler(3tcl)