From: Jonathan Turkanis (technews_at_[hidden])
Date: 2004-12-06 15:58:32
"Jody Hagins" <jody-boost-011304_at_[hidden]> wrote in message
news:20041206153207.0dd11478.jody-boost-011304_at_atdesk.com...
> On Sat, 4 Dec 2004 23:44:46 -0700
> "Jonathan Turkanis" <technews_at_[hidden]> wrote:
>
>
> > You don't need typeid -- you can just do:
> >
> > template<typename T>
> > struct unique_id_holder {
> > static char val;
> > };
> >
> > template<typename T>
> > char unique_id_holder::val;
> >
> > template<typename T>
> > int unique_id()
> > {
> > return reinterpret_cast<int>(&unique_id_holder::val);
> > }
>
>
> For "better" portability, you should make that "int" a "long."
True. Daryle mentioned the problems about the size of integral types, and I was
taking it for granted. The reason it doesn't matter much is that the
applications which could benifit from a compile-time type id could do just as
well if the id were split into several components.
> Specifically, each of the above will get a
> different ID when calling unique_id<T>() with modifiers and references,
> but they will get the "same" std::type_info for those calls.
Yes, good point. It would be nice, for several purposes, if typeid were less
forgetful.
Jonathan