This is a plugin based implementation of Daryl Koopersmith’s modular themes concept and patch
(#12877). It provides the get_template_module() function, which allows for the creation
of well-architected themes with highly reusable code. For more on the use of this function,
read Daryl’s series of posts:
If you like this method of WordPress theme design, then vote up ticket #12877. The ideal scenario is for this functionality to be provided in WordPress core. This plugin is simply a proof of concept, and provides an easy way for theme developers to start playing with modular themes. The bulk of this plugin is directly from Daryl’s patch. The one exception being the update_template_hierarchy() function, which duplicates much of the template selection logic from wp-includes/theme.php in WordPress core.