Callback to a method in a class using Structures_DataGrid_Column

Hi. Maybe this question is not PEAR specific, sorry if this is not the place to ask this. Is possible to use a callback from a class to a function defined in the same class? <?php function printCheckBox($params) { ... } .. dg->addColumn(new Structures_DataGrid_Column(null, null, null, array('width' => '10'), null, 'printCheckbox()')); .. ?> and get something like <?php class X { function printCheckBox($params) { ... } function display() { ... dg->addColumn(new Structures_DataGrid_Column(null, null, null, array('width' => '10'), null, '$this->printCheckbox()')); ... } } ?> I know second option is wrong :) but get the idea? TIA Reference: http://pear.php.net/manual/en/package.structures.structures-datagrid.example-advanced.php