title: What is a callback function and how do I use it with OOP
body: <p>I want to use the <a href="http://simplehtmldom.sourceforge.net/manual_api.htm" rel="noreferrer">php simple HTML DOM parser</a> to grab the image, title, date, and description from each article on a page full of articles. When looking at the API I notice it has a set_callback which Sets a callback function. However im not sure what this does or how I would use it? In one of the examples its used to call a function which strips out some stuff, im wondering if you have to use this to call all functions?</p>
  
  <p>I guess im wondering why I use this, and what does it do as I have never come across a callback function before!</p>