Dylan Bridgman has posted a new tutorial talking about building one of the key pieces of any framework (and most applications) to help get requests to the right place - a basic routing system.

There is always value in learning about the internals of the frameworks and libraries we use. It allows for a deeper understanding of the problem being solved and appreciation of the work that has gone into these projects. So today I will be building a basic router to explore this fundamental part of even the smallest framework. The idea is not to create something complete or production-ready but rather the minimum set of features needed to be considered a router.

He creates a simple script that handles both static and variable routes as well as throw an error when a route match isn't found. He starts off talking about the structure of URLs and shows the setup of a rewrite rule to forward all requests to an index page (where the router lives to handle them). Then he talks about the structure of the routing table and how to structure the route-to-action formatting. He opts for a simple PHP array with a closure as the action portion as a starting place. He shows how this is useful for static route matching but upgrades to regular expression matching (passed through a preg_match) to allow variables.