Nested Template Specialization

Question

Having a brain fart... Is it possible to make something like this work?

template struct Foo
{
    template struct Bar;
};

template         


        

Answer 1

As others have pointed out, C++ doesn't let you specialize a nested class if the outer class template is not also specialized. When I had a situation like that, I was able to work around it with a helper class tucked away in an internal namespace:

namespace internal {
  template  struct FooBarHelper
  { /* ... */ };
  // Specialization
  template  struct FooBarHelper
  { /* specialized version goes here */ };
}

template struct Foo
{
  template struct Bar : public internal::FooBarHelper;
};

Of course it's not quite as hidden as you might like it to be.