Tag dispatch versus static methods on partially specialised classes

Question

Suppose I want to write a generic function void f(), which does one thing if T is a POD type and another thing if T is non-PO

Answer 1

I would like tag dispatch because:

• Easy to extend with new tags
• Easy to use inheritance (example)
• It is fairly common technique in generic programming

It seems tricky to me to add third variant in second example. When you'll want to add, for example non-POD-of-PODs type you'll have to replace bool in template struct f2; with something other (int if you like =) ) and replace all struct f2 with struct f2. So that for me the second variant looks hardly extensible. Please correct me if I wrong.