Re: Curious question about the STL ostream

Hello!

So I was reading O'Reilly's C++ in a Nutshell when I came accross
something interesting:

The class definition for basic_ostream contains numerous overloaded
operator<< functions:

template <class charT, class traits = char_traits<charT> >
class basic_ostream : virtual public basic_ios<charT,traits>
{
public:
...
    basic_ostream<charT,traits>& operator<< (bool n);
    basic_ostream<charT,traits>& operator<< (short n);
    basic_ostream<charT,traits>& operator<< (int n);
...
etc.
}

which makes sense since these are used for statements like

    cout << 45 << 34 << endl;

But the functions to output strings and characters are implemented as
function templates elsewhere and *not* as member function of
basic_ostream :

template<class charT, class traits>
basic_ostream<charT,traits>& operator<< (basic_ostream<charT,traits>&
out, char c);

template<class traits>
basic_ostream<char,traits>& operator<< (basic_ostream<char,traits>& out,
char c);

Could anyone shed some light on why the STL would implement these
functions as function templates and not as memebr functions of the
basic_ostream class? (I am probably missing something bigger here, since
I'm only a fairly intermediate C++ programmer and I don't know the STL
in depth).