| [25] | 1 | '\" |
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| 2 | '\" Copyright (c) 1990-1992 The Regents of the University of California. |
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| 3 | '\" Copyright (c) 1994-1996 Sun Microsystems, Inc. |
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| 4 | '\" |
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| 5 | '\" See the file "license.terms" for information on usage and redistribution |
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| 6 | '\" of this file, and for a DISCLAIMER OF ALL WARRANTIES. |
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| 7 | '\" |
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| 8 | '\" RCS: @(#) $Id: update.n,v 1.10 2007/12/13 15:22:33 dgp Exp $ |
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| 9 | '\" |
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| 10 | .so man.macros |
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| 11 | .TH update n 7.5 Tcl "Tcl Built-In Commands" |
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| 12 | .BS |
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| 13 | '\" Note: do not modify the .SH NAME line immediately below! |
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| 14 | .SH NAME |
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| 15 | update \- Process pending events and idle callbacks |
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| 16 | .SH SYNOPSIS |
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| 17 | \fBupdate\fR ?\fBidletasks\fR? |
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| 18 | .BE |
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| 19 | |
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| 20 | .SH DESCRIPTION |
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| 21 | .PP |
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| 22 | This command is used to bring the application |
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| 23 | .QW "up to date" |
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| 24 | by entering the event loop repeatedly until all pending events |
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| 25 | (including idle callbacks) have been processed. |
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| 26 | .PP |
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| 27 | If the \fBidletasks\fR keyword is specified as an argument to the |
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| 28 | command, then no new events or errors are processed; only idle |
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| 29 | callbacks are invoked. |
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| 30 | This causes operations that are normally deferred, such as display |
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| 31 | updates and window layout calculations, to be performed immediately. |
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| 32 | .PP |
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| 33 | The \fBupdate idletasks\fR command is useful in scripts where |
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| 34 | changes have been made to the application's state and you want those |
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| 35 | changes to appear on the display immediately, rather than waiting |
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| 36 | for the script to complete. Most display updates are performed as |
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| 37 | idle callbacks, so \fBupdate idletasks\fR will cause them to run. |
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| 38 | However, there are some kinds of updates that only happen in |
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| 39 | response to events, such as those triggered by window size changes; |
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| 40 | these updates will not occur in \fBupdate idletasks\fR. |
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| 41 | .PP |
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| 42 | The \fBupdate\fR command with no options is useful in scripts where |
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| 43 | you are performing a long-running computation but you still want |
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| 44 | the application to respond to events such as user interactions; if |
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| 45 | you occasionally call \fBupdate\fR then user input will be processed |
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| 46 | during the next call to \fBupdate\fR. |
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| 47 | .SH EXAMPLE |
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| 48 | Run computations for about a second and then finish: |
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| 49 | .CS |
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| 50 | set x 1000 |
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| 51 | set done 0 |
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| 52 | after 1000 set done 1 |
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| 53 | while {!$done} { |
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| 54 | # A very silly example! |
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| 55 | set x [expr {log($x) ** 2.8}] |
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| 56 | |
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| 57 | # Test to see if our time-limit has been hit. This would |
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| 58 | # also give a chance for serving network sockets and, if |
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| 59 | # the Tk package is loaded, updating a user interface. |
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| 60 | \fBupdate\fR |
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| 61 | } |
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| 62 | .CE |
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| 63 | |
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| 64 | .SH "SEE ALSO" |
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| 65 | after(n), interp(n) |
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| 66 | |
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| 67 | .SH KEYWORDS |
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| 68 | event, flush, handler, idle, update |
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