You don't need anything like this for C++

Posted Jul 10, 2012 21:31 UTC (Tue) by cmccabe (guest, #60281)
In reply to: You don't need anything like this for C++ by jwakely
Parent article: Calling for a new openSUSE development model

It seems like the best practice is to put all of your C++ library declarations into one namespace-- for the sake of argument, call it foolib.

It seems like what you're recommending then is that you have something like this:

namespace foolib {
   namespace version1 {
       ...
   }
   inline namespace version2 {
       ...
   }
}

Given that use-case, I don't think we need to care about the scenario where there are declarations of the same name in the namespace containing the using-directive-- neither the library user nor the library implementor should be doing that.

Templates defined in an inline namespace can be instantiated and specialized as though they are members of the enclosing namespace, not possible via a using-directive.

That's fair. I suppose template specialization is where the "using directive" approach really breaks down.

The cost of this feature is that debugging becomes (even more) difficult, since you search the symbol table of your application for foolib::doit and you don't find it. Instead you find N versions and have to decide which one you're really using. But of course, none of us here writes bugs, so that shouldn't be a problem :)