tom
    <code>operator==</code> for the target class.</p>

    <h4><a name="symmetry">Symmetry</a> Note</h4>

    <p>Before talking about symmetry, we need to talk about optimizations to
    understand the reasons for the different implementation styles of
    operators. Let's have a look at <code>operator+</code> for a class
    <code>T</code> as an example:</p>
<pre>
T operator+( const T&amp; lhs, const T&amp; rhs )
{
   return T( lhs ) += rhs;
}
</pre>
    This would be a normal implementation of <code>o