title: How to associate non-member functions with a class in Doxygen?
body: <p>I'm sure there's some way to do this with the \defgroup, \addgroup and \@{ \@} tags, but after a couple of hours of trial and (obviously) error, I'm asking SO.....</p>
  
  <p>I have:</p>
  
  <pre><code>class C {
  public:
      void foo () const;
  };
  </code></pre>
  
  <p>and I have some helper non-member functions that really are part of C's interface, but aren't in the class:</p>
  
  <pre><code>std::string
  format (const C&amp; c, const std::string &amp;fmt);
  </code></pre>
  
  <p>I'd like the format function to appear on the same page as the class functions.  Is that just not possible?  Is the best I can do a "module" page, which lists C as a class (with a hyperlink to C's comments, and format as a function?</p>