title: What are inline namespaces for?
body: <p>C++11 allows <code>inline namespace</code>s, all members of which are also automatically in the enclosing <code>namespace</code>. I cannot think of any useful application of this -- can somebody please give a brief, succinct example of a situation where an <code>inline namespace</code> is needed and where it is the most idiomatic solution?</p>
  
  <p>(Also, it is not clear to me what happens when a <code>namespace</code> is declared <code>inline</code> in one but not all declarations, which may live in different files. Isn't this begging for trouble?)</p>