title: Throw runtime warnings in C++
body: <p>I started using exceptions some weeks ago and now I wonder if there is a way to just throw a warning. This warning shouldn't force the application to exit if it isn't caught. I will give you an example in what situation I would like to use that.</p>
  
  <p>There is a system that appends properties to unique ids. When I somehow try to add a property to a not yet existing id, the system should create that id internally for me, add the property to it afterwards and return the result. Of course this can't be done quietly. But since the application could stay running, I do not want to throw an exception.</p>
  
  <p>How can I notify that something wasn't quite correct, but the system runs on?</p>