Re: [boost] [typeof-users] Looking for a consistent schemeforadding Typeof support to Boost libraries

From: Peder Holt (peder.holt_at_[hidden])
Date: 2006-01-19 07:18:58

On 1/19/06, Tobias Schwinger <tschwinger_at_[hidden]> wrote:
> Peder Holt wrote:
> > On 1/19/06, Andy Little <andy_at_[hidden]> wrote:
> >
> >
> > Personally, I don't like the 2nd approach, as it introduces include
> > order dependencies,
> > <boost/a_lib/a_component.hpp> must be included prior to including
> > <boost/a_lib/typeof_support.hpp>
> >
> > Creating a header called my_includes.hpp that contains:
> > #include <boost/a_lib/a_component.hpp>
> > #include <boost/a_lib/typeof_support.hpp>
> > and in my_program.cpp including
> >
> > #include <my_includes.hpp>
> > #include <boost/a_lib/another_component.hpp>
> >
> > gives a different behaviour from
>
> There should only be a slight difference in terms of compile time -- except this
> effect the behaviour should be identical.
>
> >
> > #include <boost/a_lib/another_component.hpp>
> > #include <my_includes.hpp>
> >
> > From my perspective, this is unacceptable.
>
> I believe here's a misunderstanding. Did your read
>
>     http://article.gmane.org/gmane.comp.lib.boost.devel/136946
>
> (guessing from the time stamp you probably couldn't)?
>
>
> Or am /I/ eventually missing something?

My understanding of the solution:
1. typeof_support.hpp uses include-guard defines to filter which
components to register to typeof.
2. Any component included AFTER typeof_support.hpp will not have
typeof_support, as their include-guards have not been triggered at the
point of including typeof_support.hpp

#include <my_includes.hpp>
#include <boost/a_lib/another_component.hpp>
will not register the another_component with typeof,
but
#include <boost/a_lib/another_component.hpp>
#include <my_includes.hpp>
will.

Is there something I haven't understood?

Regards,
Peder

>
>
> Regards,
>
> Tobias
>
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