title: How do I overload += in Julia?
body: <p>I'm trying to understand how operator overloading works in Julia. The manual is quite brief, and gives <code>+()</code> as an example function, then states all the operators are overloadable with their obvious names (a list of non-obvious names is also provided).</p>
  
  <p>But what about <code>+=?</code> The function <code>+=()</code> doesn't even seem to exist, nor does <code>+=!()</code> (since it is a modifying function). I frequently overload operators in C++ by defining <code>+=</code> first and then use a simple <code>+</code> based on copy and <code>+=</code>. </p>
  
  <p>In my case I don't even think I need <code>+</code>, just the behavior of <code>+=</code>... I realize I could write my own modifying function but the operator syntax would be nice. (Out of curiosity, how do <code>*=</code>, <code>/=</code>, <code>$=</code>, etc work?)</p>