DevShed continues their look at design patterns in PHP with this last installment of their Memento pattern series - "Using the Memento Pattern with a File Reading Class".

Let me now introduce the topics that I'll be covering in this last article of the series. I'll show you how to use the memento pattern to keep track of some properties that correspond to a file reading class. In this way we'll construct a flexible mechanism for moving back and forth between file lines.

They create both of the needed classes for the pattern to work - the originator and the caretaker class - to handle the reading of the files. The code for both is pretty cut and paste-able, so there's no problem getting your example to work. With those constructed, they tie them together with an example of the design pattern in action - reading and displaying the lines of a text file to the user.