Remember register globals? Remember how you had to code as if it was off, because it might be? Remember how you had to consider the security implications of it being on, because it might be? The might be and might not be is something which has plagued a lot of early PHP features. Register globals is in no way alone in this, in the effort of making things versatile the PHP developers managed to introduce the worst of both worlds and the best of none. At least for code where you can’t guarantee 100% control over the environment your code would be running in.
We see this even today with things such as short open tags. Ever been told you shouldn’t use them? Yeah, that’s primarily because they could be turned off thus leaking your source code into the document. (To a lesser degree it’s also about XML incompatibility)
Today I want to cover a very known feature, which many people don’t often think of as being in the same group as register globals and short open tags. Namely path info. The idea of path info is brilliant enough, it is most often used as a way to have SEO “friendly” URIs in cases where one might not be able to rewrite the URL. In short, you can have a URI like so: