Templates
Separating code from HTML can be difficult in PHP. As we discussed in Chapter 1 and have shown throughout this book, one of the best features of PHP is that scripts can be embedded anywhere in HTML documents. However, this can lead to maintenance problems: if we want to redesign the presentation of the web site, then we may need to rewrite code or, at the very least, understand how PHP and HTML are interleaved in the application. This also makes it difficult to maintain code when it is interleaved with presentational components.
A good solution for medium- to large-scale web database applications is to use templates to separate markup and code. In this section, we illustrate how templates can be used in PHP applications through a case study example from the online winestore. In our example, we use the open source XTemplate class library available from http://sourceforge.net/projects/xtpl/. The XTemplate library is object-based, and Chapter 2 provides a brief introduction to the object-oriented features of PHP. There are other excellent template libraries, including most notably the Smarty PHP template engine available from http://www.phpinsider.com/php/code/Smarty/.