使用“extern模板”时，对模板进行专门化的正确方法是什么？

I am hoping someone can point out the correct way to specialize a method in a template class while using "extern template class" and "template class" for explicit instantiation with gnu c++. I've tried to boil down this problem with the simplest example that mimics my real problem. It appears that declaring "extern template" implies a template instantiation which causes errors when specializing methods. Given a driver program:I am hoping someone can point out the correct w