71 lines
2.9 KiB
Plaintext
71 lines
2.9 KiB
Plaintext
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'\"
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'\" Copyright (c) 1990 The Regents of the University of California.
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'\" All rights reserved.
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'\"
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'\" Permission is hereby granted, without written agreement and without
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'\" license or royalty fees, to use, copy, modify, and distribute this
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'\" documentation for any purpose, provided that the above copyright
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'\" notice and the following two paragraphs appear in all copies.
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'\"
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'\" IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY
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'\" FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
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'\" ARISING OUT OF THE USE OF THIS DOCUMENTATION, EVEN IF THE UNIVERSITY OF
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'\" CALIFORNIA HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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'\"
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'\" THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY WARRANTIES,
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'\" INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
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'\" AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
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'\" ON AN "AS IS" BASIS, AND THE UNIVERSITY OF CALIFORNIA HAS NO OBLIGATION TO
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'\" PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
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'\"
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'\" $Header: /user6/ouster/wish/man/RCS/tkerror.n,v 1.6 93/07/09 11:36:38 ouster Exp $ SPRITE (Berkeley)
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'/"
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.so man.macros
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.HS tkerror tk 7.0
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.BS
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'\" Note: do not modify the .SH NAME line immediately below!
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.SH NAME
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tkerror \- Command invoked to process background errors
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.SH SYNOPSIS
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\fBtkerror \fImessage\fR
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.BE
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.SH DESCRIPTION
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.PP
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The \fBtkerror\fR command doesn't exist as built-in part of Tk. Instead,
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individual applications or users can define a \fBtkerror\fR
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command (e.g. as a Tcl procedure) if they wish to handle background
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errors.
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.PP
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A background error is one that occurs in a command that didn't
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originate with the application. For example, if an error occurs
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while executing a command specified with a \fBbind\fR of \fBafter\fR
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command, then it is a background error. For a non-background error,
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the error can simply be returned up through nested Tcl command
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evaluations until it reaches the top-level code in the application;
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then the application can report the error in whatever way it
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wishes. When a background error occurs, the unwinding ends in
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the Tk library and there is no obvious way for Tk to report
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the error.
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.PP
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When Tk detects a background error, it invokes the \fBtkerror\fR
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command, passing it the error message as its only argument.
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Tk assumes that the application has implemented the \fBtkerror\fR
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command, and that the command will report the error in a way that
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makes sense for the application. Tk will ignore any result returned
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by the \fBtkerror\fR command.
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.PP
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If another Tcl error occurs within the \fBtkerror\fR command
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then Tk reports the error itself by writing a message
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to stderr.
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.PP
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.VS
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The Tk script library includes a default \fBtkerror\fR procedure
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that posts a dialog box containing the error message and offers
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the user a chance to see a stack trace that shows where the
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error occurred.
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.VE
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.SH KEYWORDS
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background error, reporting
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