[boost] Re: is_base_and_derived question

From: Andrei Alexandrescu (andrewalex_at_[hidden])
Date: 2003-01-28 12:14:23

"Gennaro Prota" <gennaro_prota_at_[hidden]> wrote in message
news:11sc3v069sbatf5dlo8j3hrpg1so6ksnma_at_4ax.com...
> On Tue, 28 Jan 2003 03:06:35 -0800, "Andrei Alexandrescu"
> <andrewalex_at_[hidden]> wrote:
>
> >"Thomas Witt" <witt_at_[hidden]> wrote in message
> >news:3E3590ED.8030100_at_ive.uni-hannover.de...
> >> IIUC is_based_and_derived<T,T> evaluates to true as well. Is a class T
> >> strictly speaking a base class of itself?
> >
> >Yes
>
> That's a convention of is_base_and_derived though. To the standard a
> class is not a base of itself, so this convention should be
> documented. In other words, you have to specify whether the ordering
> is strict or not.

True. I'd just note that in language theory, a type is always considered its
own supertype because that makes it much easier to reason everywhere else.

Andrei