PHP: What does this error mean? Abstract method must be compatible?
<p>I have an abstract class. I'm extending that class. I'm getting this error:</p>

<pre><code>Fatal error: Declaration of Default_Model_FoobarMapper::_setClassVarsFromRow() must be compatible with that of Default_Model_AbstractMapper::_setClassVarsFromRow() in /location/to/models/FoobarMapper.php on line 3
</code></pre>

<p>What does this usually mean?</p>

<p><strong>Update:</strong> Found out that my type hinting was throwing an error. You can't do this:</p>

<pre><code>abstract class MyAbstractClass
{
    abstract protected function _myFunction($array, $generic_class);
}

class Foobar extends MyAbstractClass
{
    protected function _myFunction($array, Specific_Class $specific_class)
    {
        //etc.
    }
}
</code></pre>
