Tcl_CancelIdleCall man page on QNX

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Tcl_DoWhenIdle(3)	    Tcl Library Procedures	     Tcl_DoWhenIdle(3)


       Tcl_DoWhenIdle,	Tcl_CancelIdleCall - invoke a procedure when there are
       no pending events

       #include <tcl.h>

       Tcl_DoWhenIdle(proc, clientData)

       Tcl_CancelIdleCall(proc, clientData)

       Tcl_IdleProc   *proc	   (in)	     Procedure to invoke.

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

       Tcl_DoWhenIdle  arranges	 for  proc  to be invoked when the application
       becomes	idle.	The  application  is  considered  to  be   idle	  when
       Tcl_DoOneEvent has been called, couldn't find any events to handle, and
       is about to go to sleep waiting for an event to occur.  At  this	 point
       all  pending  Tcl_DoWhenIdle  handlers  are  invoked.  For each call to
       Tcl_DoWhenIdle there will be a single call  to  proc;   after  proc  is
       invoked	the  handler is automatically removed.	Tcl_DoWhenIdle is only
       usable in programs that use Tcl_DoOneEvent to dispatch events.

       Proc should have arguments and result that match the type Tcl_IdleProc:
	      typedef void Tcl_IdleProc(ClientData clientData);
       The clientData parameter to proc is a copy of the  clientData  argument
       given to Tcl_DoWhenIdle.	 Typically, clientData points to a data struc‐
       ture containing application-specific information about what proc should

       Tcl_CancelIdleCall  may be used to cancel one or more previous calls to
       Tcl_DoWhenIdle:	if there is a Tcl_DoWhenIdle  handler  registered  for
       proc  and clientData, then it is removed without invoking it.  If there
       is more than one handler on the idle  list  that	 refers	 to  proc  and
       clientData,  all	 of the handlers are removed.  If no existing handlers
       match proc and clientData then nothing happens.

       Tcl_DoWhenIdle is most useful in situations where (a) a piece  of  work
       will  have  to be done but (b) it's possible that something will happen
       in the near future that will change what has  to	 be  done  or  require
       something  different to be done.	 Tcl_DoWhenIdle allows the actual work
       to be deferred until all pending events have been processed.   At  this
       point  the exact work to be done will presumably be known and it can be
       done exactly once.

       For example, Tcl_DoWhenIdle might be used by an editor to defer display
       updates	until  all pending commands have been processed.  Without this
       feature, redundant redisplays might occur in some situations,  such  as
       the processing of a command file.

       At  present  it	is  not safe for an idle callback to reschedule itself
       continuously.  This will interact badly with  certain  features	of  Tk
       that  attempt to wait for all idle callbacks to complete.  If you would
       like for an idle callback to reschedule itself continuously, it is bet‐
       ter to use a timer handler with a zero timeout period.

       callback, defer, idle callback

Tcl				      7.5		     Tcl_DoWhenIdle(3)
                             _         _         _ 
                            | |       | |       | |     
                            | |       | |       | |     
                         __ | | __ __ | | __ __ | | __  
                         \ \| |/ / \ \| |/ / \ \| |/ /  
                          \ \ / /   \ \ / /   \ \ / /   
                           \   /     \   /     \   /    
                            \_/       \_/       \_/ 
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