This is an extremely simple (only 9 lines), straightforward, easy to read, understand and maintain front controller for PHP, which routes requests to functions (actions).

It uses convention over configuration making life a breeze (see below)

PHP Source Code

include 'app/boot.php';

$action = $_SERVER['REQUEST_URI'] == '' ? 'home' : trim($_SERVER['REQUEST_URI']);
$function_name = trim(str_replace(['-'], '_', $action), '/');

@include_once 'app/pages/' . $function_name . '.php';

if (function_exists($function_name.'_action')) {
    die(($function_name.'_action')());
}

// Page not found
include_once 'app/pages/page_not_found.php';
die(page_not_found_action());

Conventions Used

1. Every request is redirected to an action file, which responds to the request

2. Every action file contains an action function ending in _action , which will be called

3. Once the action file is called the request is killed

4. The action files are placed in a single folder /app/pages

How to use?

The controller will route the requests as follows

All not found requests will be redirected to the page not found action.

Examples

1. Home page

function home_action() {
    return 'Hello world';
}

2. Page not found page

function page_not_found_action() {
    return 'Page not found: ' . $_SERVER['REQUEST_URI'];
}

2. Contact page

function contact_action() {
    if (is('post')) {
        // Validate submtted contact form
        // Send contact notification
        // Redirect        
    }

    return include('contact_form.phtml');
}

Extra Helping Functions

Here are some extra functions you may add to your boot.php file.

function is($requestAction) {
    return $_SERVER['REQUEST_METHOD'] == strtoupper(trim($requestAction));
}

function redirect($path){
    header('Location:'.$path);
    exit;
}