I’ll give you a rant about PHP 5.3′s “latest” addition of namespaces. I think this is a harmful concept in PHP, a “new” feature that needs to be understood correctly before using. My short advice for all PHP developers is: DO NOT USE NAMESPACES. I’ve seen many PHP developers in our own company and customer projects, who have started to use namespaces just fort the sake that they are new, and not knowing what they are really doing. With my background as a Java developer I can give a better perspective.
In Java there is an actual use for namespaces. Java features package visibility, which I nowadays favor over public or protected (and protected over private) because package visibility (and namespaces) can be used to create nice unit tests by putting the tested class and unit test in the same namespace. In PHP there is no package visibility, so there is no need for namespaces.
In Java, the namespaces (packages) are a very rigid system that cannot be configured in any way. However, the greatness of PHP is that there is a very dynamic and powerful mechanism called autoloader, which can be used to configure your “namespaces” as you wish. A typical legacy way to build PHP package-like -structures was for example in ZendFramework a convention to put conceptual modules in separate directories, and have an autoloader to load the classes from the corresponding directory.
However, now when an actual namespace is implemented in PHP core, many developers like to give it a try and start to use it everywhere. The outcome is that all good parts of PHP start to fade away. The classes start to get polluted with useless boilerplate just for the sake of having namespaces. Useless, hard-to-read and difficult to write use-statements have appeared to PHP classes from C and Java (and other legacy 3rd generation low-productivity languages). This is clearly bad at least from project management and productivity perspective.
When you are using PHP namespaces, all changes to everything become difficult. You are also lacking IDE tools from Java that would auto-generate your “use” statements. Since there is no real benefit in using namespaces, you will just shoot yourself in your own leg by using namespaces in PHP.
The only legitimate use of namespaces that comes in my mind is when you develop some open source, abstract, non-concrete (see http://stackoverflow.com/questions/1031135/what-is-abstractness-vs-instability-graph ) library software that would be included to your composer.json by thousands of other projects. However, if you are developing your own, concrete, non-library software for your customer or own use, all classes that you define should be in your “root namespace” and adding any other namespaces will just make you hurt. You are not probably going to offer your software publicly available to the Internet, in which case there is no need to publish a public namespace to the world, and slow your development work by adding all the boilerplate required to do so. In 99% of the cases you are doing the first, and you don’t need any namespaces for you own software.
So, DO NOT USE NAMESPACES IN PHP, unless you know what you are doing.