Freek Van der Herten has a post to his site showing how PHP functions can (sort of) be overloaded with the help of a trait from Adam Wathan.
PHP does not support method overloading. In case you’ve never heard of method overloading, it means that the language can pick a method based on which parameters you’re using to call it. This is possible in many other programming languages like Java, C++.
However, with some clever coding, Adam Wathan made a trait, aptly called Overloadable, that makes method overloading possible. It works by just accepting any parameters using the splat operator and then determining which of the given functions must be called according to the given parameters.
He shows how to use the trait in a simple example, defining a single "bar" function and using the "Overloadable" trait to handle the switching between the methods based on the input variables. You can find more information about the trait and the source for it in this gist over on GitHub.