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<hr>
<h1>cl:debug:mv</h1>
<hr>
<p>The <nobr>cl:<b>debug:mv</b></b></nobr> function can be used to debug
multiple value expressions:</p>
<p><div class="box">
<dl>
<dt>(cl:<b>debug:mv</b> <i>expr</i></dt>
<dd><i>expr</i> - a Lisp expression, returning an arbitrary number of values<br>
returns - the normal Lisp return value from evaluating <i>expr</i></dd>
</dl>
</div></p>
<pre class="example">
(defun <font color="#0000CC">cl:debug:mv</font> (expr)
(setq <font color="#AA5500">cl:*multiple-values*</font> nil)
(let ((result (eval expr)))
(format t <font color="#880000">";; cl:*multiple-values* => ~a~%"</font> <font color="#AA5500">cl:*multiple-values*</font>)
(format t <font color="#880000">";; *rslt* => ~a~a~%"</font> <font color="#AA5500">*rslt*</font>
(if <font color="#AA5500">cl:*multiple-values*</font> <font color="#880000">"" " [invalid]"</font>))
result))
</pre>
<p>The <nobr>cl:<b>debug:mv</b></nobr> function first sets the
<nobr><a href="global-multiple-values.htm">cl:*multiple-values*</a></nobr>
variable <nobr>to <a href="../../reference/nil.htm">NIL</a></nobr>, then it
evaluates the expression. After evaluation it prints the values of the
<nobr><a href="global-multiple-values.htm">cl:*multiple-values*</a></nobr>
and <a href="../../reference/global-rslt.htm">*rslt*</a> variables and
returns the normal Lisp return value from the evaluation.</p>
<p>Example:</p>
<pre class="example">
> (cl:debug:mv '(cl:values 1 2 3))
;; cl:*multiple-values* => T
;; *rslt* => (1 2 3)
1
> (cl:debug:mv 1)
;; cl:*multiple-values* => NIL
;; *rslt* => (1 2 3) [invalid]
1
</pre>
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