Re: [boost] [Test] [All Library Developers] multiple definitions

David Abrahams wrote:

namespace whatever { class foo {};

template <class T, int = 0>

Wonderful solution! However, I wonder what the default template argument here (int = 0) is for?

struct unique_instance { T& get() { static T x; return x; }; };

namespace { foo& bar = unique_instance<foo>::get(); } }