Standard PHP Library (SPL) is a collection of interfaces and classes that are meant to solve standard problems and implements some efficient data access interfaces and classes. When PHP 5 was initially released, it included a strong sense of standardization introduced in the core package. This can be a real time saver when common programming issues must be solved through proven, standard solutions. That’s precisely the case with iterators, since the SPL package includes many predefined iterating classes that can be used for traversing different data structures, without having to reinvent the wheel over and over again.
- Introduction to SPL – phpro.org
- Iterators – eide.org
- Iterators in PHP5 – ramikayyali.com
- SPL Iterators – zend.com
- Iterators and SPL – etutorials.org