Extern templates

A template specialization can be explicitly declared as a way to suppress multiple instantiations. For example:

1. #include "MyVector.h"
3. extern template class MyVector<int>; // Suppresses implicit instantiation below --
4. // MyVector<int> will be explicitly instantiated elsewhere
6. void foo(MyVector<int>& v)
7. {
8. // use the vector in here
9. }

The “elsewhere” might look something like this:

1. #include "MyVector.h"
3. template class MyVector<int>; // Make MyVector available to clients (e.g., of the shared library

This is basically a way of avoiding significant redundant work by the compiler and linker.