Re: [boost] Re: FC++ Formal review is now in progress (2/13-2/23)

From: Gabriel Dos Reis (gdr_at_[hidden])
Date: 2004-02-14 16:16:22

David Abrahams <dave_at_[hidden]> writes:

| Gabriel Dos Reis <gdr_at_[hidden]> writes:
| 
| > If you follow the first principle that scopes nest, then the "C" in
| > the altenrative #1 gets hidden by the member S<>::C in the local scope of
| > S<>::f()-body (current situation).   If you want something different, 
| > you'll end up with a notion similar to "parallel scopes" or
| > "injection of enclosing scope into the enclosed scopes" (which is
| > contrary to "scopes nest").
| 
| You could just use the rule that each template parameter list forms
| a scope that encloses whatever it adorns.

Yes.  And that is what we currently have and that leads to the member
name hides the enclosing template-parameter name rule.

There are two observations to make:
  (1) in order to "minimize surprises", there is an additional rule
      saying that it is not permitted to (directly) redeclare a
      template-parameter name in the scope it adorns.

  (2) the cases where there still are surprises (The case David
      Vandevoorde posted) is when the member-name comes from a base
      class.  This case may be surprising to some because names  in
      base classes are not directly declared  -- therefore  point (1)
      can't apply.  Rather, they are found through lookup that proceeds
      from inner-to-outer scope search. 

I believe that the proposed rule about invalid template-parameter
renaming is a minimal damage to the general "scopes nest" principle.

| Then the reading that's obvious to me follows "from first principles".

That would work for member templates (assuming we change/clarify the
current rules) but it would not resolve the issue  mentioned by David
Vandevoorde to his satisfaction.

-- Gaby