Custom PHP Exceptions for Unimplemented Code

I’ve written about Custom PHP Exceptions before - as well as using PHP Interfaces for code readability. There’s one coding pattern that I use pretty consistently that encompasses these concepts - a custom exception for code or functionality that is not yet written.

There are times when you have work that is in the ’todo’ state where a simple @todo comment won’t suffice. You don’t want this method called because it’s not done!

Or perhaps you are extending a class but don’t want some of the functionality to work in your altered implementation.

Both of these are great examples of places where you can use a custom exception. This will allow you to stop the code and give context to the programmer.

The custom exception I like to use looks like this - very simple:

<?php

namespace App\Exceptions;

use RuntimeException;

class NotImplementedException extends RuntimeException {}

That’s it! It’s from a base SPL Runtime Exception. It clearly indicates that this code is not done. For example…

public function doSomething($thing)
{
  $this->process(ucwords($thing));
}

public function doSomethingElse($string)
{
  throw new NotImplementedException(__METHOD__ . ' says not for you!');
}