Re: [boost] [Test] [All Library Developers] multiple definitions

From: Gennadiy Rozental (gennadiy.rozental_at_[hidden])
Date: 2005-06-21 00:43:14

"David Abrahams" <dave_at_[hidden]> wrote in message 
news:u1x6xgong.fsf_at_boost-consulting.com...
>
> I just tried to compile something with the test library and two
> translation units.  Boom!  It was this definition, which appears in
> boost/test/impl/execution_monitor.ipp.

I wonder which Boost.Test componenent were you using?

> signal_handler* signal_handler::s_active_handler = NULL; //!! need to be 
> placed in thread
> specific storage

I would prefer to fix this post release.

> have this problem.  The answer is to initialize a *reference* in the
> unnamed namespace to a single, common object:
>
>  namespace whatever
>  {
>    class foo {};
>
>    template <class T, int = 0>
>    struct unique_instance
>    {
>        T& get()
>        {
>            static T x;
>            return x;
>        };
>    };
>
>    namespace
>    {
>      foo& bar = unique_instance<foo>::get();
>    }
>  }

This is an idiom I am using  in Boost.Test's trivial_singleton.hpp.

Here is a solution for the issue above:

=====================================
struct active_signal_handler_t : public singleton<active_signal_handler_t> {
    signal_handler* _;
private:
    BOOST_TEST_SINGLETON_CONS( active_signal_handler_t );
};

BOOST_TEST_SINGLETON_INST( active_signal_handler )
=====================================

active_signal_handler._ is s_active_handler above.

Gennadiy