'\"
'\" Copyright (c) 1990-1992 The Regents of the University of California.
'\" Copyright (c) 1994-1996 Sun Microsystems, Inc.
'\"
'\" See the file "license.terms" for information on usage and redistribution
'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
'\" 
'\" RCS: @(#) $Id: update.n,v 1.2 2003/11/24 05:10:00 bbbush Exp $
'\" 
'\" The definitions below are for supplemental macros used in Tcl/Tk
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.TH update 3tcl 7.5 Tcl "Tcl Built-In Commands"
.BS
'\" Note:  do not modify the .SH NAME line immediately below!
.SH NAME
update \- 处理等待的事件和空闲回调
.SH "总览 SYNOPSIS"
\fBupdate\fR ?\fBidletasks\fR?
.BE

.SH "描述 DESCRIPTION"
.PP
这个命令重复的进入事件循环直到处理了所有的等待事件(包括空闲回调)，以此使应用成为“最近更新的”。
.PP
如果指定 \fBidletasks\fR 关键字为给这个命令的一个参数，则不处理新事件或错误；只调用空闲回调。这导致通常被推延的操作，比如显示器更新和窗口格局计算，被立即进行。
.PP
\fBupdate idletasks\fR 命令在一些脚本中有用，在其中对应用的状态做了变更并且你想要这些变化立即出现在显示器上，而不是等待脚本完成。多数显示器更新被作为空闲回调来进行，所以 \fBupdate idletasks\fR 将导致他们运行。但是，有些种类的更新只发生在对事件的响应当中，比如窗口大小变更所触发的事件；在 \fBupdate idletasks\fR 中将不发生这些更新。
.PP
没有选项的\fB update\fR 命令在一些脚本中有用，在其中你想运行一个长时间的运算而仍想让应用响应事件比如用户交互；如果你偶尔的调用 \fBupdate\fR，则在下次调用 \fBupdate \fR期间将处理用户输入。

.SH "参见 SEE ALSO"
after(n), bgerror(n)

.SH "关键字 KEYWORDS"
event, flush, handler, idle, update

.SH "[中文版维护人]"
.B 寒蝉退士
.SH "[中文版最新更新]"
.B 2001/11/20
.SH "《中国 Linux 论坛 man 手册页翻译计划》:"
.BI http://cmpp.linuxforum.net
.SH "跋"
.br
本页面中文版由中文 man 手册页计划提供。
.br
中文 man 手册页计划：\fBhttps://github.com/man-pages-zh/manpages-zh\fR