How can I set the value of an attribute?

Tuesday 05 April 2005 12:50:14 pm

I need the subject of forum_reply has the value "RE: {$parent.name}".

I fetch the parent by

{let parent=fetch(content, node, 
     hash(node_id, $object.current.main_parent_node_id))}

Now, How can I set the value of attribute $object.data_map.subject to $parent.name?

So, when I call edit template, the input "subject" is filled with this value.

Thanks in advance
Adolfo Barragan