Re: [boost] [flyweight] Review period extended to February 3

From: Joaquín Mª López Muñoz (joaquin_at_[hidden])
Date: 2008-02-01 09:32:26

"vicente.botet" ha escrito:

> Hi,
>
> I was wondering if as the intermodule_holder is a kind of workaround for
> platforms where dynamic loaded libraries can duplicate static libraries, we
> can have a better performance on the others for free.
>
> On platforms on which static variables are unique inter dynamic loaded
> modules the intermodule_holder specifier can be a static_holder.
> This could be controlled using conditional compilation.
>
> struct intermodule_holder:holder_marker
> {
>   template<typename C>
>   struct apply
>   {
> #ifdef BOOST_NO_DLL_UNIQUE_STATIC_VARIABLE
>     typedef intermodule_holder_class<C> type;
> #else
>     typedef static_holder_class<C> type;
> #endif
>   };
> };
>
> Have this a sens or I'm missing something?
> Could the documentation add a reference to the duplication problem?

This makes sense, but I lack expertise on this area, and don't really
know which platforms or compilers avoid symbol duplication.
If someone can help here I'll be happy to add this optimization.

> In addition, I'd replace static_holder by intramodule_holder.
> intramodule_holder reflects much more the accessibility intent for the
> users, static_holder talks more about  the implementation.

Do you mean that intermodule_holder should be the default rather
than static_holder? There are reasons not to do that, as I explained
to John Reid at:

http://lists.boost.org/Archives/boost/2008/01/132814.php

Joaquín M López Muñoz
Telefónica, Investigación y Desarrollo