[Typo3] <itemsProcFunc> in flexform?

[joachim rinck]

Hi there,

I've been searching for hours now but I don't find anything that makes 
my itemsProcFunc work in flexform. It is working in ext_tables.php but I 
really want the value to be stored in flex. Also i recently read that 
adding fields to tt_content for some extension is highly discouraged.

Could someone please help me, point me to working documentation or send 
me a working example? Here is my flexform and the itemsprocfunc code:

     <tx_persons_select>
      <TCEforms>
       <label>person</label>
         <config>
             <type>select</type>
             <items type="array">
                 <numIndex index="0" type="array">
                     <numIndex index="0">LIST</numIndex>
                     <numIndex index="1">LIST</numIndex>
                 </numIndex>
             </items>
             <minitems>0</minitems>
             <maxitems>1</maxitems>
             <size>3</size>
             <itemsProcFunc>class.tx_persons_select->main</itemsProcFunc>
         </config>
      </TCEforms>
     </tx_persons_select>


and:

class tx_persons_select {
     var $id;
function main(&$params,&$pObj)  {
     $sSelect = 'uid, firstname, infix, surname ';
     $sFrom = 'tx_persons_person';
     if(t3lib_div::_GP("tdebug")) {
         $this->id = t3lib_div::_GP('id');
         $this->id = 208;
         echo "<b>flexform query</b> line: ".__LINE__.",  file: ".__FILE__ ;
         echo "<br><div style=\"color:#ff0000\">";
         echo 
$GLOBALS['TYPO3_DB']->SELECTquery($sSelect,$sFrom,$sWhere,'','');
         echo "</div><br>";
         //echo t3lib_div::debug($aFlexData,'aFlexData');
     }
     $aSelect=array();
     $dRes = 
$GLOBALS['TYPO3_DB']->exec_SELECTquery($sSelect,$sFrom,'','','');
     $i=1;
     $params['items']=Array();
     $params['items'][]=Array('Select a person for the TIP',0);
     while ($aResult = $GLOBALS['TYPO3_DB']->sql_fetch_assoc($dRes)) {
             $fullname = $aResult['firstname'].' '.$aResult['infix'].' 
'.$aResult['surname'];
             $params['items'][]=Array($fullname, $aResult['uid']);
     }

}//function main
}//class

Please help! Thanks a lot,
Joachim