Detect generic base class

29 Apr 2010

      Hi list,

how can I detect if a class inherits from a generic class? E.g.,

template <class Derived>
class base {};

class final: public base<final> {};

I would like to specialise a type trait for all classes deriving from
base<whatever>, possibly using enable_if and is_base_of:

template 
class trait: boost::false_type {};

// What syntax here? Something like this (which does not work):
template 
class trait >::type>:
boost::true_type {};

The best I've come up with has been putting a typedef for Derived in
base, and then using SFINAE:

template <class Derived>
class base {
  public:
    typename Derived derived;
};

template <class T>
class trait
...
::type>: boost::true_type {};
But this is ugly and I'm sure there are much better ways of doing this :)

Thanks in advance,

  Francesco

Francesco Biscani