Re: %prefix with C++ namespaces

[Hans Aberg]

On 2 Oct 2007, at 19:55, Joel E. Denny wrote:

> > > > I do not think the leading "::"-issue is very important - but it  
> > > > would be
> > > > nice
> > > > showing one has given thought to it. :-)
> > >
> > > So, I'm seeing no reason to disallow it.  If the user wants absolute
> > > references, he should probably get absolute references.
> >
> > It is OK with me whatever you do. Admitting a leading "::", and  
> > merely
> > stripping it out in the "namespace" nesting seems fine.
>
> Given this comment and given our discussion about how wrapping  
> parser.cc
> in a namespace probably won't ever work, I think we agree that the  
> leading
> "::" is redundant where Bison uses the user-supplied namespace to  
> generate
> a namespace declaration.  That is, the outermost namespace is  
> always the
> global namespace.

Right. Until somebody finds a well motivation for otherwise :-).

> Where Bison uses the user-supplied namespace as a reference, I'm now
> thinking it should use the same approach.  That is, the outermost
> namespace should always be the global namespace.  The only way to  
> be sure
> of this is for Bison to add a leading "::" if it's not already there.
> For example, the C++ skeleton #define's YYSTYPE to a name that  
> starts with
> the user-supplied namespace.  If the user uses YYSTYPE in a scope  
> other
> than the global scope, the reference might be ambiguous unless the  
> leading
> "::" is there.

I suggest don't worry about it: in references, keep it as the user  
enters it. No obligation approach. This somebody can experiment with  
it, and perhaps can clarify it better.

> The YYSTYPE situation I've described may be rare, but I think it  
> shows why
> this approach is cleaner.  If the namespace declarations must assume a
> leading "::", then so should the references.  In other words, `%define
> namespace "NS"' should consistently interpret NS relative to the  
> global
> namespace.

Then you do not have to worry about things like this. Let the C++  
compiler take care of it.

  Hans Aberg