[boost] Re: typeof: type registration

From: Arkadiy Vertleyb (vertleyb_at_[hidden])
Date: 2004-07-22 11:22:09

"David Abrahams" <dave_at_[hidden]> wrote

> "Arkadiy Vertleyb" <vertleyb_at_[hidden]> writes:
> > ultimately, at some point, somebody is writing a CPP file.  This end
user
> > has to collect all such headers, and "chain" them in a single header,
thus
> > emulating a single enum.
>
> That sounds like a serious usability problem to me.  Furthermore,
> we'll still have an ODR violation if two separately-compiled libraries
> do the chaining in different ways.  Am I wrong?

Right, but it does provide the ability to create the ODR-complient code
(even if only inside one module) by
applying certain discipline...  And I don't quite agree that this discipline
is too hard to follow.  People use system-wide enums left and right...  and
in many cases this is just classes from a couple of libraries that the user
really needs.

As for separately-compiled libraries, do you think such a library could have
any remaining traces of the template instantiations we are discussing?

Futhermore, without the discipline, provided people don't care about ODR, it
can be made almost as easy as automatic registration.  For example the
registration headers can directly #include the "enum"-headers, so that if
they wern't previously chained, they chain in a random way.  Even automatic
ID-generation faciities can be provided in addition, for end-users who do
not care about ODR.

But, as it was said here yesturday, I think we should not punish "I know
what I am
doing" group.  Let's at least provide the ability to create the
ODR-complient code...

Arkadiy