The ability for a class to inherit from multiple parents is maligned by many, but can be a good thing in some situations. For those working in PHP, multiple inheritance has never been an option; classes are limited to one parent, though they can implement many other datatypes through the use of interfaces. Interfaces can lead to code duplication in improperly-factored inheritance hierarchies. Even in well-architected hierarchies, multiple classes that implement similar methods can contain a lot of overlap.

He starts with a definition of what traits are and where their real usefulness is (as well as what should be the difference between a class and a trait). He gives an example of a typical hierarchy where two classes extend a parent but then they both need the same functionality. Code duplication's not a possibility and inheritance make run into exposure issues. Traits come to the rescue by dropping in just the feature you need when you need it. His example code shows adding some logging to a simple class via a "Logging" trait and a "Singleton trait" example.

Stefan has since tweaked the proposal and in the latest version it includes an alternative approach called Grafts along with the original Traits idea, which is essentially language level delegation pattern support. I am absolutely sure that we will either see Traits or Grafts in the next non patch release of PHP (aka 5.4 or 6.0).

Lukas would like to see the support go in sooner than later, so he requests some comments and thoughts on the proposed functionality and to leave them as comments on his blog entry.

I thought it might be interesting to write an article about the performance-enhancing tips you probably don't want to hear about - that is, those that are most likely to produce measurable (and durable) results but do require some effort on your part.

His list consists of:

• You Don't Need To Plan Ahead In Order To Have A Plan
• Combat Database Abuse
• Do You Really Need A Database Anyway?
• Scale Horizontally
• Refactor To Scale Vertically