The Standard PHP Library (SPL) is a powerful set of tools that are often overlooked. It is very common to see an SPL talk at conferences, but those talks usually just introduce each SPL class to the audience without giving some real world examples. I am going to show you a real world example on how to use SPL FilterIterator in an ecommerce website.
The namespace operator in PHP 5.3 is a backslash (\). One of the criticisms of this operator is that the code starts to look like directory paths on Windows. The added side benefit of this is that spl_autoload() knows how to autoload classes that use a namespace style that matches the directory layout.