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72 lines
2.8 KiB
Groff
72 lines
2.8 KiB
Groff
'\"
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'\" Copyright (c) 1995-1996 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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'\" SCCS: @(#) CrtModalTmt.3 1.3 96/03/25 20:00:19
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'\"
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.so man.macros
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.TH Tcl_CreateModalTimeout 3 7.5 Tcl "Tcl Library Procedures"
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.BS
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.SH NAME
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Tcl_CreateModalTimeout, Tcl_DeleteModalTimeout \- special timer for modal operations
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.SH SYNOPSIS
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.nf
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\fB#include <tcl.h>\fR
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.sp
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\fBTcl_CreateModalTimeout\fR(\fImilliseconds, proc, clientData\fR)
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.sp
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\fBTcl_DeleteModalTimeout\fR(\fIproc, clientData\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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.BE
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.SH DESCRIPTION
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.PP
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\fBTcl_CreateModalTimeout\fR provides an alternate form of timer
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from those provided by \fBTcl_CreateTimerHandler\fR.
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These timers are called ``modal'' because they are typically
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used in situations where a particular operation must be completed
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before the application does anything else.
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If such an operation needs a timeout, it cannot use normal timer
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events: if normal timer events were processed, arbitrary Tcl scripts
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might be invoked via other event handlers, which could interfere with
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the completion of the modal operation.
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The purpose of modal timers is to allow a single timeout to occur
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without allowing any normal timer events to occur.
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.PP
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\fBTcl_CreateModalTimeout\fR behaves just like \fBTcl_CreateTimerHandler\fR
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except that it creates a modal timeout.
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Its arguments have the same meaning as for \fBTcl_CreateTimerHandler\fR
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and \fIproc\fR is invoked just as for \fBTcl_CreateTimerHandler\fR.
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\fBTcl_DeleteModalTimeout\fR deletes the most recently created
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modal timeout; its arguments must match the corresponding arguments
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to the most recent call to \fBTcl_CreateModalTimeout\fR.
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.PP
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Modal timeouts differ from a normal timers in three ways. First,
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they will trigger regardless of whether the TCL_TIMER_EVENTS flag
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has been passed to \fBTcl_DoOneEvent\fR.
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Typically modal timers are used with the TCL_TIMER_EVENTS flag
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off so that normal timers don't fire but modal ones do.
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Second, if several modal timers have been created they stack:
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only the top timer on the stack (the most recently created one)
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is active at any point in time.
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Modal timeouts must be deleted in inverse order from their creation.
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Third, modal timeouts are not deleted when they fire: once a modal
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timeout has fired, it will continue firing every time \fBTcl_DoOneEvent\fR
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is called, until the timeout is deleted by calling
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\fBTcl_DeleteModalTimeout\fR.
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.PP
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Modal timeouts are only needed in a few special situations, and they
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should be used with caution.
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.SH KEYWORDS
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callback, clock, handler, modal timeout
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