[Boost-users] Re: Using MPL towriteis_derived_from_std_basic_ostream

From: Jonathan Turkanis (technews_at_[hidden])
Date: 2004-09-03 11:41:29

"David Abrahams" <dave_at_[hidden]> wrote in message:
> "Jonathan Turkanis" <technews_at_[hidden]> writes:
>
> > "David Abrahams" <dave_at_[hidden]> wrote in message

> >> It's hard for me to understand why you would need has_xxx for this
> >> purpose, or how you would use it.
> >
> > Well, you could look at the attachment .... ;-)
>
> I did, but got mired in details.

<snip>

> Why not just copy the implementation of is_base_and_derived and
> templatize the conversion operators in the Host class?

I thought of that. I liked the posted version because it just uses out-of-the
box components. Maybe it just doesn't look mired in details to me because I
wrote it :-).

BTW, the first macro BOOST_IO_BOOL_TRAIT_DEF in the attachement is not relevant
to the current discussion. The macro BOOST_IO_IOS_TRAIT_DEF conatins the entire
implementation of the above technique.

Jonathan