How does Stroustrup's Can_Copy template work?

Question

Stroustrup provides a Can_copy template. How does it work?

template struct Can_copy {
    static void constraints(T1 a, T2 b) { T2          


        

Answer 1

Meant to be informative, not an answer (not deserving of an upvote):

In C++0x you will have improved facilities for this in the header .

std::is_copy_constructible::value;
std::is_copy_assignable::value;
std::is_constructible::value;
std::is_assignable::value;
std::is_convertible::value;

http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2010/n3225.pdf

search for "[meta]".