repo_zf1/documentation/manual/en/module_specs/Zend_Exception-Previous.xml

<?xml version="1.0" encoding="UTF-8"?>
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<sect1 id="zend.exception.previous">
    <title>Previous Exceptions</title>

    <para>
        Since Zend Framework 1.10, <classname>Zend_Exception</classname> implements the
        <acronym>PHP</acronym> 5.3 support for previous exceptions. Simply put, when in a
        <methodname>catch()</methodname> block, you can throw a new exception that references the
        original exception, which helps provide additional context when debugging. By providing this
        support in Zend Framework, your code may now be forwards compatible with
        <acronym>PHP</acronym> 5.3.
    </para>

    <para>
        Previous exceptions are indicated as the third argument to an exception constructor.
    </para>

    <example id="zend.exception.previous.example">
        <title>Previous exceptions</title>

        <programlisting language="php"><![CDATA[
try {
    $db->query($sql);
} catch (Zend_Db_Statement_Exception $e) {
    if ($e->getPrevious()) {
        echo '[' . get_class($e)
            . '] has the previous exception of ['
            . get_class($e->getPrevious())
            . ']' . PHP_EOL;
    } else {
        echo '[' . get_class($e)
            . '] does not have a previous exception'
            . PHP_EOL;
    }

    echo $e;
    // displays all exceptions starting by the first thrown
    // exception if available.
}
]]></programlisting>
    </example>
</sect1>
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