docsrc/xlisp/xlisp-doc/reference/baktrace.htm


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<html><head><title>XLISP baktrace</title>

<link rel="stylesheet" type="text/css" href="reference.css">

</head>

<body>

<a href="../start.htm">Nyquist / XLISP 2.0</a>&nbsp; -&nbsp;
<a href="../manual/contents.htm">Contents</a> |
<a href="../tutorials/tutorials.htm">Tutorials</a> |
<a href="../examples/examples.htm">Examples</a> |
<a href="reference-index.htm">Reference</a>

<hr>

<h1>baktrace</h1>

<hr>

<p><table cellpadding="0" cellspacing="0" style="margin-left:10px"><tbody>
<tr valign="top">
  <td><nobr>Type:</nobr></td>
  <td><nobr>&nbsp;&nbsp;-&nbsp;&nbsp;</nobr></td>
  <td width="100%"><nobr>function (subr)</nobr></td>
</tr>
<tr valign="top">
  <td><nobr>Source:</nobr></td>
  <td><nobr>&nbsp;&nbsp;-&nbsp;&nbsp;</nobr></td>
  <td width="100%"><nobr>xldbug.c, xlsys.c</nobr></td>
</tr>
</tbody></table></p>

<h2>Syntax</h2>

<p><div class="box">

<dl>
<dt>(<b>baktrace</b> [<i>level</i>])</dt>
<dd><i>level</i> - an optional integer expression<br>
returns - <a href="nil.htm">NIL</a></dd>
</dl>

</div></p>

<h2>Description</h2>

<p> The 'baktrace' function is used to examine the system execution stack
from within the
<nobr><a href="../manual/xlisp.htm#break-loop">Break Loop</a>.</nobr> It
shows the nested forms that got the system to the current state. The
<nobr><a href="../manual/xlisp.htm#break-loop">Break Loop</a></nobr> can be
entered by a system error, or by the Nyquist/XLISP
<a href="error.htm">error</a>, <a href="cerror.htm">cerror</a>, or
<a href="break.htm">break</a> functions. <nobr>If the</nobr> 'levels'
parameter is not specified, all the nested forms will be shown back to the
main loop form that started the execution. <nobr>If 'level'</nobr> is
specified the most recent 'level' nested forms will be shown.</p>

<h2>Examples</h2>

<pre class="example">
(defun out (x)
  (print x)
  (mid 99))

(defun mid (x)
  (print x)
  (in 999))

(defun in (x)
  (print x)
  (break "in" x))  <font color="#008844">; break</font>

&gt; (out 9)
9
99
999
<font color="#AA0000">break: in - 999</font>
<font color="#AA0000">if continued: return from BREAK</font>

1&gt; (baktrace)   <font color="#008844">; the 1 before the &gt; indicates a break loop</font>
Function: #&lt;Subr-BAKTRACE: #9af6688&gt;
Function: #&lt;Subr-BREAK: #9af6778&gt;
Arguments:
  "in"
  999
Function: #&lt;Closure-IN: #9b99574&gt;
Arguments:
  999
Function: #&lt;Closure-MID: #9b99670&gt;
Arguments:
  99
Function: #&lt;Closure-OUT: #9b99778&gt;
Arguments:
  9
NIL
</pre>

<p>See also:</p>

<ul>
<li><nobr>Contents &rarr; <a href="../manual/contents.htm#debugging-and-error-handling">Debugging and Error Handling</a></nobr></li>
<li><nobr>XLISP 2.0 Manual &rarr; <a href="../manual/xlisp.htm#break-loop">Break Loop</a></nobr></li>
</ul>

<p><nobr>&nbsp;&nbsp;<a href="#top">Back to Top</nobr></a></p>

<hr>

<a href="../start.htm">Nyquist / XLISP 2.0</a>&nbsp; -&nbsp;
<a href="../manual/contents.htm">Contents</a> |
<a href="../tutorials/tutorials.htm">Tutorials</a> |
<a href="../examples/examples.htm">Examples</a> |
<a href="reference-index.htm">Reference</a>

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