[boost] Re: [Config] proposal of new macro, BOOST_DECL :follow up for boost::noncopyable & vc7.1 & dll

From: Francis ANDRE (francis.andre_at_[hidden])
Date: 2004-11-03 09:07:44

> Except we only have one definition for non_copyable, so what happens if
> library X wants it to have a dll interface and lib Y doesn't?  It's also
all

You'r right...so a solution could be to ask to the provider of each dll
boost libraries to embed
each declaration of an imported class with the followings win32 only pragmas

#pragma warning(disable: 4275 4251)
class BOOST_THREAD_DECL mutex
: private noncopyable {
//....
};
#pragma warning(default: 4275 4251)

so that any missing __declspec(dllimport) in any user's dll library could be
trapped as an error!!

Francis
-- 
A good friend will come bail you out of jail..........
but, a true friend....will be sitting next to you saying:
 "...that was fun."
"John Maddock" <john_at_[hidden]> a écrit dans le message de
news:01fe01c4c1a4$fd9e64f0$49f90c52_at_fuji...
> > When using the boost.thread package as a dll under vc7.1, one gets for
> > each
> > reference of boost::mutex  the C4275 warning for the inherited
noncopyable
> > class (in fact 5 times, one for mutex, one for timed_mutex, one for
> > try_mutex, one for thread, and one for thread_group!!)
> >
> > c:\boost\include\boost-1_32\boost\thread\mutex.hpp(34) : warning C4275:
> > non - DLL-interface 'boost::noncopyable_::noncopyable' used as base for
> > DLL-interface 'boost::mutex'
> >
> > In order to avoid such warning, it would be nice to redefine -- 
> > again(sic) -- the BOOST_DECL macro and put it as a decorator for all
> > dependent classes used by the boost libraries that could be generated as
a
> > dll.(thread, regex, filesystem, and so on).
> >
> > With the empty string as default value in boost/config.hpp, it would the
> > responsability of each boost libraries to setup BOOST_DECL to the
correct
> > value when using it as a dll.
>
> Except we only have one definition for non_copyable, so what happens if
> library X wants it to have a dll interface and lib Y doesn't?  It's also
all
> inline, so declaring it imported is a little strange.  Maybe some #pragmas
> to disable the warnings would be better, especially as we can't do much
> about:
>
> c:\data\boost\develop\boost\boost\thread\thread.hpp(75) : warning C4251:
> 'boost::thread_group::m_threads' : class 'std::list<_Ty>' needs to have
> dll-interface to be used by clients of class 'boost::thread_group'
> with
> [
> _Ty=boost::thread *
> ]
>
> John.
>
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