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Tcl_CreateTimerHandler(3)    Tcl Library Procedures    Tcl_CreateTimerHandler(3)

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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 be-
					       fore invoking proc.

     Tcl_TimerProc *proc (in)		       Procedure to  invoke  after  mil-
					       liseconds 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).
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DESCRIPTION
     Tcl_CreateTimerHandler  arranges for proc to be invoked at a time millisec-
     onds 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 mil-
     liseconds:  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_Timer-
     Proc:

	    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  in-
     formation 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  pe-
     riod has already elapsed and proc has been invoked then Tcl_DeleteTimerHan-
     dler  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(n), Tcl_CreateFileHandler(3), Tcl_DoWhenIdle(3)

KEYWORDS
     callback, clock, handler, timer

Tcl				       7.5	       Tcl_CreateTimerHandler(3)

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