Drupal 7 Module Development

Theming a Module
if (is_array($elements['#items'][$key]['data'])) {
$elements['#items'][$key]['data'] =
drupal_render($elements['#items'][$key]['data']);
}
}
return $elements;
}
In our single_blog_item_list_child_render() function, we simply loop through
all the #items, determine if they have an array in their data element and call
drupal_render() on its contents.
Attaching CSS to render arrays
If you look at the screenshot of the first version, you can see that the default styling
of our block is less then inspiring, so let's tweak that by giving our content some
sensible default styling by adding a CSS stylesheet.
Since version 5, Drupal has had a drupal_add_css() function to add CSS stylesheets
to pages. What's new in Drupal 7 is that, due to Drupal's block and page caching and
the capabilities of hook_page_alter(), we now need to attach our stylesheet directly
to the render element that we are creating. If we were to use drupal_add_css(), the
stylesheet would not be cached with its block and it would also be considerably more
difficult to alter the stylesheet if a hook_page_alter() implementation desired
to (For example if it removed the block and wanted to remove the CSS too.)
So instead of calling drupal_add_css() from within our
single_blog_block_view() function, we add it to the returned render array:
// Add a CSS file to style the block.
$block['content']['#attached']['css'][] = drupal_get_path('module',
'single_blog') . '/single-blog.css';
We use drupal_get_path() to find the path to our module relative to the website
root. The #attached array can contain a list of CSS files and JS files to attach to
our render element. For JavaScript files, just append them to the js array via
['#attached']['js'][].
And here are the contents of our single-blog.css stylesheet:
/* $Id$ */
.block-single-blog .content ul {
padding-left: 0; /* LTR */
}
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