title: When to Overload the Comma Operator?
body: <p>I see questions on SO every so often about overloading the comma operator in C++ (mainly unrelated to the overloading itself, but things like the notion of sequence points), and it makes me wonder:</p>
  
  <p>When <em>should</em> you overload the comma? What are some examples of its practical uses?</p>
  
  <p>I just can't think of any examples off the top of my head where I've seen or needed to something like</p>
  
  <pre><code>foo, bar;
  </code></pre>
  
  <p>in real-world code, so I'm curious as to when (if ever) this is actually used.</p>