Lack of interest Not editable datawriter fields

[xf_phantom]

What about a new key for the _getfields method to be able to define a field as "not changeable/editable".
I want to be able to define a field while the record creation, but non other part of the application "should" be able to change this via the datawriter.(i'm aware that this won't be needed very often and that the definition in the dw is still not 100% secure because another coder could run a sql query and change the field, but at least the datawriter api wouldn't allow this and other devs working with our api would see, that this feeld shouldn't be thouched).

ATM we're checking this inside of the _preSave method, but it would be much easier & less code, if the xf datawriter would provide this
e.g.

protected function _getFields()
   {
     return array(
       'foo' => array(
         'edit_history_id' => array('type' => self::TYPE_UINT, 'autoIncrement' => true),
         'name_type'  => array('type' => self::TYPE_STRING, 'editable'=>false
       )
     );
   }
[/php]