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markom |
'\"
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'\" Copyright (c) 1990 The Regents of the University of California.
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'\" Copyright (c) 1994-1996 Sun Microsystems, Inc.
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'\"
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'\" See the file "license.terms" for information on usage and redistribution
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'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
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'\"
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'\" RCS: @(#) $Id: CrtTimerHdlr.3,v 1.1.1.1 2002-01-16 10:25:23 markom Exp $
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'\"
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.so man.macros
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.TH Tcl_CreateTimerHandler 3 7.5 Tcl "Tcl Library Procedures"
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.BS
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.SH NAME
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Tcl_CreateTimerHandler, Tcl_DeleteTimerHandler \- call a procedure at a
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given time
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.SH SYNOPSIS
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.nf
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\fB#include \fR
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.sp
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Tcl_TimerToken
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\fBTcl_CreateTimerHandler\fR(\fImilliseconds, proc, clientData\fR)
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.sp
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\fBTcl_DeleteTimerHandler\fR(\fItoken\fR)
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.SH ARGUMENTS
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.AS Tcl_TimerToken milliseconds
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.AP int milliseconds in
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How many milliseconds to wait before invoking \fIproc\fR.
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.AP Tcl_TimerProc *proc in
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Procedure to invoke after \fImilliseconds\fR have elapsed.
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.AP ClientData clientData in
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Arbitrary one-word value to pass to \fIproc\fR.
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.AP Tcl_TimerToken token in
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Token for previously-created timer handler (the return value
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from some previous call to \fBTcl_CreateTimerHandler\fR).
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.BE
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.SH DESCRIPTION
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.PP
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\fBTcl_CreateTimerHandler\fR arranges for \fIproc\fR to be
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invoked at a time \fImilliseconds\fR milliseconds in the
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future.
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The callback to \fIproc\fR will be made by \fBTcl_DoOneEvent\fR,
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so \fBTcl_CreateTimerHandler\fR is only useful in programs that
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dispatch events through \fBTcl_DoOneEvent\fR or through Tcl commands
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such as \fBvwait\fR.
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The call to \fIproc\fR may not be made at the exact time given by
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\fImilliseconds\fR: it will be made at the next opportunity
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after that time. For example, if \fBTcl_DoOneEvent\fR isn't
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called until long after the time has elapsed, or if there
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are other pending events to process before the call to
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\fIproc\fR, then the call to \fIproc\fR will be delayed.
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.PP
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\fIProc\fR should have arguments and return value that match
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the type \fBTcl_TimerProc\fR:
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.CS
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typedef void Tcl_TimerProc(ClientData \fIclientData\fR);
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.CE
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The \fIclientData\fR parameter to \fIproc\fR is a
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copy of the \fIclientData\fR argument given to
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\fBTcl_CreateTimerHandler\fR when the callback
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was created. Typically, \fIclientData\fR points to a data
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structure containing application-specific information about
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what to do in \fIproc\fR.
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.PP
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\fBTcl_DeleteTimerHandler\fR may be called to delete a
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previously-created timer handler. It deletes the handler
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indicated by \fItoken\fR so that no call to \fIproc\fR
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will be made; if that handler no longer exists
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(e.g. because the time period has already elapsed and \fIproc\fR
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has been invoked then \fBTcl_DeleteTimerHandler\fR does nothing.
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The tokens returned by \fBTcl_CreateTimerHandler\fR never have
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a value of NULL, so if NULL is passed to \fBTcl_DeleteTimerHandler\fR
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then the procedure does nothing.
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.SH KEYWORDS
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callback, clock, handler, timer
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