In lack of better words, I'll call this compositional programming style. It's a style which is usually more prevalent with experienced programmers. [...] There is, however, a dark side to composition - dependencies.

He starts with a definition to bring everyone up to a level field then moves on to how their used (through a "global symbol" or directly passed in) and how they can "leak" if you're not careful.

To help protect you and your code from any kind of damage down the line, Troels suggests making a container to keep objects where they need to be. He even includes an example with namespace support to make things even easier down the road.

An experienced PHP developer might be wondering why posting this topic in a blog if PHP already has universal and almost transparent tools for this job [...] The key statement here is "almost transparent" which means you have to include all class definitions before invoking unserialize or use some __autoload schema.

The whole problem is due to the fact a serialized object has no idea about its class definition except the class name(the reason behind that is absolutely valid). [...] That's why I decided to hack up, hopefully, a more universal solution to this problem

His method contains things inside of a "serialization container" that automagically includes everything needed before it gets serialized. His code for the method is included as well as some examples of its use.

Most compiled languages that I have used have some kind of container implementation, Lists, Maps, Trees, Stacks and all their many variations. PHP has arrays and the SPL.

The only problem he's noted so far is that containers made in userland would be slower than ones created natively. A comment from Antony Dovgal points out a project similar to what he's looking for that's already in the works.

PEAR::Auth is a package that allows you to abstract the user authentication from the main part of your application and not worry about it. What is good about the package is that it comes with different "containers" that allows you to authenticate users against different storages.

So I played around with creating an SAP container that allows you to check users against your company's SAP system and for example build a section of your Internet (or Extranet) page that is only accessible for people and partners that exist as users in the SAP system.

There's an extension to PHP you'll need to get and install, but with that in place, it's as simple as setting the authentication type to "SAP" and giving it the hostname to connect to. He also includes some sample scripts to get you started, including the Auth_Container_SAP class that makes the magic happen.