The usort function in PHP allows you to sort data based on the results of a function that you define. But if you are using OO PHP and you want to avoid functions, it turns out you can use methods of objects too with a slight variation to the usort call. The usual call to usort looks something like this:

usort($arrayToBeSorted, 'theNameOfAFunction');

If you want to use a method in an object to act as the sorting function, you can do so by making the call like this:

usort($arrayToBeSorted, array('theNameOfAnObject', 'theNameOfAMethod'));

You can also use this type of calling if the sorting method exists in the object that you are calling it from within. To do this, use this format:

usort($arrayToBeSorted, array($this, 'theNameOfAMethod'));

Happy sorting!