Luca Risolia wrote:
> On 19/06/2012 21:30, Gerhard Fiedler wrote:
>> Is there a way to define this template function so that it is only
>> instantiated for classes that implement this print() function? (I could
>> make the name such that it is very unlikely that any other class has
>> such a name.)

> Yes, there is a way:

> #include <type_traits>

> template < class Printable,
>          typename std::enable_if<std::is_member_function_pointer
>             <decltype(&Printable::print)>::value, int>::type= 0 >
> std::ostream &operator<<( std::ostream &stream,
>     Printable const &printable )
> {
>     printable.print( stream );
>     return stream;
> }