Referencing objects that have yet to be defined
<p>I've got two objects that need to point to one another... the only problem is that since they are declared in a particular order, one or the other doesn't know about the other object existing. For example:</p>

<pre><code>...
#define foobar_h

class Foo {
  Bar* b;
};

class Bar {
  Foo* f;
};

...
</code></pre>

<p>How can I declare these classes so that they'll be happy referencing one another?</p>
