In this new post on Ben Ramsey's blog today, he shares his experiences with SimpleXML, mentioning specifically some of the undocumented functions that he's noticed.
I was very excited today while glancing through the code in ext/simplexml/simplexml.c to find some, as of yet, undocumented methods in PHP's SimpleXMLElement class. This discovery came after I've spent several hours over the last couple of nights banging my head against the desk to figure out a way to create a class that extends SimpleXMLElement and adds a new method for adding a child, which would have to use DOM in order to work—or so I thought.
Of course, it's wasn't as easy as it seemed, and Ben soon found some of the limitations of the SimpleXML library. Of course, he did manage to find a way to add new children to the document you're working with (something that normally would have required the intervention of the DOM functionality). Check out the post for a code example.