function ajaxMain($funcName, $var1 = '', $var2 = '', $var3 = '', $var4 = '', $var5 = '')
{
	switch($funcName)
	{
		case 'showUser':
			$tab->add(TabInnerHtml::getBehavior('content',showUser($var1)));
		break;
		case 'showTopic':
			$tab->add(TabInnerHtml::getBehavior('content',showTopic($var1,$var2)));
		break;
	}
	return $tab->getString();
}

<a href="#" onclick="ajaxMain('showTopic',<?=$id?>,<?=$parent_id?>);return false;">lala</a>