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 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 use-ful useful
ful 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.
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 applica-tion-specific application-specific
tion-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_DeleteTimerHan-dler Tcl_DeleteTimerHandler
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.
KEYWORDS
callback, clock, handler, timer
Tcl 7.5 Tcl_CreateTimerHandler(3)
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