One of the nice things about iterators is the ability to shove them into other iterators, allowing you to wrap their functionality in other functionality to return a more precise result set. Take for example the idea that we want to read a directory to list only the images inside of it. There are two main ways to do this, via readdir functions and via FilesystemIterator objects. Going the FilesystemIterator route, one common way seems to be extend another class called FilterIterator which allows you to customize a filter based on you overwriting a method called accept().

He shows not only overriding the "accept" method, but also the constructor to make using this new iterator a much simpler (and cleaner) call. You can find out more about the FilesystemIterator (and others) over in the Iterators section of the PHP manual.

In this article I detail the process by which you can set up your controller actions in Zend Framework 2 to return either the default HTML, or JSON data depending on the "Accept Header" in the request. It incorporates changes related to a security update added since this very helpful article was written, and expands on some of the intricacies of making your web layer objects better "json providers."

His example uses a "ViewJsonStrategy" and the criteria to look for to determine which version to respond with (HTML or JSON) - the Accept header. It uses the JSON encoder/decoder instead of the built-in PHP one to he could use the included "toJson" method to customize the output of the JSON instead of just returning everything.

There are four primary systems that need to be set up and isolated. And they are described by the acronym DTAP-Development, Testing, Acceptance, and Production. One thing that has changed recently, though, is that these systems no longer have to mean separate hardware.

He gives an overview of each, setting out definitions to be used for the rest of the series with the next part discussing some of the "smaller moving pieces" of the process.