Drupal 7 Module Development

Theming a Module
Converting a theme call to a render element was rather painless, no? Let's add
some more content to our block. Drupal core's blog module provides a page (and
menu callback) that displays teasers of recent blog posts at the path /blog. Since
menu callbacks aren't part of the theme system, we're going to leave that page
unimplemented, but let's pretend that we did implement it. In that case, our block
should provide a more link that goes to the blog page.
Adding additional content to a render element is easy. Since our $block['content']
is a single render element, we first need to move that existing render element as a child
element, which we can do by moving it to $block['content']['list']. The list
name is just an arbitrary label that we are giving to a child element; as long as it doesn't
start with a #, it doesn't matter much what we call it. We'll add our new more link as
a sibling to the list child:
// Theme the list of blog entries.
$block['content']['list'] = array(
'#theme' => 'item_list__single_blog',
'#items' => $items,
);
// Add a link to the full list of blog entries.
$block['content']['more'] = array(
'#theme' => 'more_link',
'#url' => 'blog',
'#title' => t('Read the latest blog entries.'),
);
Glancing back at our common theme hooks list, you should have noticed the
more_link theme hook which we used for our block's more link. Again we just need
to examine the documentation for theme_more_link to determine how to structure the
child element. See http://api.drupal.org/api/function/theme_more_link/7.
Creating a pre_render function
Now looking at our content, you'll probably notice that there is one piece of content
that is still locked up in a string instead of being modifiable in a render element:
the data element of each of the $items passed to our item_list render element.
Converting the l() call to a render element is again straightforward; just change
the following line:
'data' => l($node->title, 'node/' . $node->nid),
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