[php]//要实现的功能，create_function()中调用该类的_func方法???处怎么写？
class demo {
var $_p = '';

function demo($p = '') {
$this->_p = $p;
}

function _func($var) {

return md5($this->_P.$var);
}

function test() {
$str = 'abcaaaphphpaa';
echo preg_replace_callback('/(phphp)/',create_function(???,????),$str);
}
}

$d = new demo('phphp');
$d->test();[/php]