Template-fu, Zen Linking

Welcome, weary traveller.

Please, enter the dojo. Have some tea. Sit, and listen to me expound on the state of linking today.

There are a number of new techniques for linking in C+11. Some are not widely known. Some require long nights, on cold drafty mountain tops to fully master.

The new forms:

1. Extern Template

When you want white. Nothing. A truly private implementation, with only the API exported. Use extern template on class specializations to tell the compiler to not implicitly instantiate any symbols when the class is used by user code. For template functions as well.

Smartly done on forward-declarations, after the main class has been defined, making them post-declarations.  Pretty much anything goes: the syntax is the same as the syntax for explicit instantiations. Precisely because the two are a matched pair: with the power to prohibit instantiations comes the responsibility to explicitly instantiate them in some form. Wax on, wax off.

With C++11, extern template is portable. GNU C++ users have used it widely since 2002.

2. -fvisibility=hidden

And why it’s different from extern template. There seems to be a lot of confusion out there, about this. And let’s face it, the syntax is atrocious! Absolutely abominable.

GNU extensions, apply as attribute on namespaces.

3. constexpr

Mantis-style.

4. Namespace association. Tarsier-style.

But I will not bore you, weary traveller. Sit and enjoy your beverage. There will be plenty of time to talk about new techniques and methods later, after you have rested from your voyage.