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<h1>xsl:try</h1>
<p>The <code>xsl:try</code> instruction is new in XSLT 3.0: in conjunction with <code>xsl:catch</code> it allows
recovery from dynamic errors.</p>
<p>The following example shows how to recover from an error in evaluating an XPath expression (in this case, divide-by-zero):</p>
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<code>
<xsl:try select="salary div length-of-service">
<xsl:catch errors="err:FAOR0001" select="()"/>
</xsl:try></code>
</pre>
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<p>The following example shows how to recover from an error in evaluating a sequence of XSLT instructions (in
this case, a validation error):</p>
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<code>
<xsl:try>
<xsl:copy-of select="$result" validation="strict"/>
<xsl:catch>
<xsl:message>Warning: validation of result document failed:
Error code: <xsl:value-of select="$err:code"/>
Reason: <xsl:value-of select="$err:description"/>
</xsl:message>
<xsl:sequence select="$result"/>
</xsl:catch>
</xsl:try>
</code>
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<p>The <code>errors</code> attribute of <code>xsl:catch</code> indicates which error codes are caught. If absent, or it set to
<code>*</code>, all errors are caught. The value can be a whitespace-separated list of QNames; the wildcards <code>*:local</code>
or <code>prefix:*</code> can also be used.</p>
<p>It is possible to have more than one <code>xsl:catch</code> within an <code>xsl:try</code>; the first one that matches the error
is used.</p>
<p>Within the <code>xsl:catch</code>, a number of variables are available in the namespace
<code>http://www.w3.org/2005/xqt-errors</code>:</p>
<ul>
<li>
<p>err:code - the error code as a QName</p>
</li>
<li>
<p>err:description - the error description (error message)</p>
</li>
<li>
<p>err:value - the error object (if available)</p>
</li>
<li>
<p>err:module - the URI of the stylesheet module in which the error occurred</p>
</li>
<li>
<p>err:line-number - the line-number of the source stylesheet where the error occurred</p>
</li>
<li>
<p>err:column-number - for Saxon this will generally be unknown (-1)</p>
</li>
</ul>
<p>The error can be re-thrown by using the <code>error()</code> function.</p>
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