Tcl_CreateTimerHandler

Prepared by Ready-to-Run Software, Inc. 

Tcl_CreateTimerHandlerTcl Library Procedures 7.5

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NAME
     Tcl_CreateTimerHandler, Tcl_DeleteTimerHandler - call a pro-
     cedure at a given time

SYNOPSIS
     #include <tcl.h>

     Tcl_TimerToken
     Tcl_CreateTimerHandler(milliseconds, proc, clientData)

     Tcl_DeleteTimerHandler(token)

ARGUMENTS
     int              milliseconds   (in)      How   many    mil-
                                               liseconds  to wait
                                               before    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  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  com-
     mands  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 isn't 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.



Tcl                                                             1







Prepared by Ready-to-Run Software, Inc. 

Tcl_CreateTimerHandlerTcl Library Procedures 7.5

     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  struc-
     ture  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.


KEYWORDS
     callback, clock, handler, timer

































Tcl                                                             2



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