Preprocess functions setup variables to be placed within template files. Template files are meant to be simple, with simple php conditional logic, and minimal code. As a general rule of thumb, logic should be placed within preprocess functions and the output assigned to variables which are then printed within the template file.

One of the powers of preprocessors comes with the ability to quickly alter a variety of templates without the need to create additional template files. The more template files a theme has, the harder it is to maintain, understand and debug. Preprocess functions simplify a theme drastically by greatly reducing the number of needed template files.

This session will be highly focussed on samples, providing 'real-world' examples of how preprocess functions can be utilized to save time and energy while theming.