On the CodeWall blog they've posted a tutorial showing how to create a single action controller in a Laravel-based application to isolate functionality that can be called directly with no method required.

There are some magical functions in PHP, and __invoke is one of them.

Through this __invoke method, we can create classes with just one function __invoke in them, and whenever their object is called it will directly call the __invoke method, it means you don’t have to manually say $obj->someFunction() .

The post starts by talking about the Single Responsibility Principle (SRP) and how having an isolated controller with just an __invoke method. It then walks you through the implementation and how to use a controller like this. In their example they show how to use it to create "post" records (like for a blog). The post also includes some of the drawbacks of using this kind of controller including the fact that you cannot use resource routing with it.