Tcl_CreateTimerHandler(3) Tcl (7.5) 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 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).
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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
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 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.
Page 1 (printed 2/19/99)
Tcl_CreateTimerHandler(3) Tcl (7.5) Tcl_CreateTimerHandler(3)
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.
KEYWORDS
callback, clock, handler, timer
Page 2 (printed 2/19/99)
