The draft for the Strings library has an odd description of operator+
in section 21.1.1.10.1, where it says:

 template<class charT, class traits, class Allocator>
   basic_string<charT,traits,Allocator>
     operator+(const basic_string<charT,traits,Allocator>& lhs,
        const basic_string<charT,traits,Allocator>& rhs);
 Returns lhs.append(rhs).

If you look back as 21.1.1.8.2, basic_string::append, you see that
basic_string::append() is a non-const member function, which means
that it can't be used to implement operator+(), for which lhs is
a const object.  It wouldn't make sense anyway, because that would
duplicate the functionality of basic_string::operator+= (see
21.1.1.8.1).  Don't we want operator+ to create an entirely new
object, not just append to lhs?

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/* Bob Kline                                       Stream International */
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