<HTML><HEAD><TITLE>Tk Built-In Commands - report-error manual page</TITLE></HEAD>
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<H2><IMG ALIGN=BOTTOM SRC="./Img/ManPageGreen.gif"> report-error</H2>
<I>Command invoked to process errors</I><P><IMG ALIGN=TOP SRC="./Img/line-red.gif">
<H3><A NAME="M2">SYNOPSIS</A></H3>
(<B>report-error </B><I>head message obj</I>)<BR>
<H3><A NAME="M3">DESCRIPTION</A></H3>
<B>Report-error</B> is called by the interpreter when an error occurs.
This procedure is written in Scheme and can be by an application which
needs to handle redefined to handle errors. The <I>head</I> argument is
a string which identify the kind of error. The <I>head</I> argument
contains the error message and <I>obj</I> contains the object which
causes the error (or the empty list when there is no object to incriminate).
<P>
The STk library includes a default <B>report-error</B> procedure
that posts a dialog box containing the error message and offers
the user a chance to see a stack trace showing where the
error occurred and its associated environment..
<P>
If an error occurs while is <B>report-error</B> execution, the
interpreter detect that the procedure is buggy and it redirect further
messages on the standard error port.
<P>
Hereafter is a simple non-graphical error reporter.
<PRE>(define (report-error head message obj)
(let ((port (current-error-port)))
;; Display message
(format port "~A: ~A ~S\n\n" head message obj)
;; Display stack
(let ((stack (%get-eval-stack))
(env (%get-environment-stack)))
(for-each (lambda (x y) (format port "~A ~A\n" x (uncode y)))
env
stack))))</PRE>
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