Using feed title as mapping source (e. g. map to CCK field)

I've made a bit of progress. It seems the best way to use feed item inheritance, rather than mapping.

In FeedsNodeProcessor.inc, function getInheritors(), I added:

    $inheritors['feedtitle'] = array(
      'name' => t('Feed title'),
      'description' => t('The Feed title defined by the user will be copied to a CCK field named feed, if available.'),
      'callback' => 'feeds_inherit_feedtitle',
    );

And then I added the callback function:

function feeds_inherit_feedtitle($item_node, $feed_node) {
  if (!isset($item_node->field_feed) ) {
     $item_node->field_feed = $feed_node->title;
  }
}

This fails with an unusual error message, because I'm using $item_node->field_feed. If I use something else like $item_node->title, it's OK. Can anyone suggest how I might poke the value into a CCK field? Sorry, I'm a total newbie. The error message is below:

An error occurred. /batch?id=21&op=do <br /> <b>Fatal error</b>: Cannot unset string offsets in <b>/var/www/paperfeed.org/sites/all/modules/cck/content.module</b> on line <b>1248</b><br />
(Yes, the html tags show up unrendered)

Changed the name of the issue, to avoid misleading mention of mapping.

Some further progress. The following syntax works for setting the CCK field (see previous comment):
$item_node->field_feed[0]['value'] = $feed_node->title;

Please consider this issue closed as far as I'm concerned.

I'd like to reopen this issue - I still feel it adds a lot of value to the module if feed items can inherit the title of the feed they come from. I think I was incorrect in closing it earlier when I found a workaround.

Sorry if I have overstepped the bounds of etiquette here. I'm very new to drupal.org.