Question

I’ve the following:

template <template <typename, typename> class C, class T, class A >
class TTCTest
{
public:
        TTCTest(C<T, A> parameter) { /* ... some stuff... */ }
        C<T, A> _collection;
};

I want to ensure that the template is only instantiated where the T and A classes are of a specific type (path and allocator respectively).

For example:

...
list<path, allocator<path> > list1;
list<int, allocator<int> > list2;

TTCTest<list> testvar(list1); // ...should work
TTCTest<list> testvar(list2); // ...should not work
...

Is this possible and what is the syntax?

Regards,
Col

Answer 1

You can do that with partial specialisation, where you fail to provide an implementation for the non-specialised case.
For example:

template <template <typename, typename> class C, class T, class A >
class TTCTest;

template <template <typename, typename> class C>
class TTCTest<C, path, allocator<path> >
{
  // ...
};