Re: [Boost-users] [Boost.TypeTraits] Adding specialisations

John Maddock wrote:

Kirit Sælensminde wrote:

...

I'm wondering if finding the need to add specialisations of boost::detail::function_traits_helper is a result of missing headers, incorrect usage or just things that have not been added to Boost.TypeTraits on purpose?

Not added on purpose: function_traits works for *function types*, and not *pointer to function types*.

So:

functions_traits OK. function_traits bad: argument not a function type.

You can always use remove_pointer to strip a function-pointer down to a function type.

HTH, John.

That makes perfect sense, unfortunately it doesn't help. From the worker thread example I've removed the specialisation for R(**)(void) - I can't work out why there is a double indirection there, but it might well be contributing to the problem. I've also changed the functor that does the type handling to this: template< typename F > boost::shared_ptr< Future< typename boost::function_traits< F

::result_type > > operator()( F f ) { return run< typename boost::function_traits< typename boost::remove_pointer< F >::type >::result_type >( f ); }

And even to this: template< typename F > boost::shared_ptr< Future< typename boost::function_traits< F

::result_type > > operator()( F f ) { return run< typename boost::function_traits< typename boost::remove_pointer< typename boost::remove_pointer< F >::type >::type ::result_type >( f ); }

I get exactly the same error in either case: 1>e:\dev\trunk\clients\kirit saelensminde\samples\boost cookbook\worker thread\worker thread.cpp(112) : warning C4355: 'this' : used in base member initializer list 1>e:\dev\boost\install\basic\include\boost-1_34\boost\type_traits\function_traits.hpp(170) : error C2504: 'boost::detail::function_traits_helper<Function>' : base class undefined 1> with 1> [ 1> Function=int (__cdecl **)(void) 1> ] 1> e:\dev\trunk\clients\kirit saelensminde\samples\boost cookbook\worker thread\worker thread.cpp(209) : see reference to class template instantiation 'boost::function_traits<Function>' being compiled 1> with 1> [ 1> Function=int (__cdecl *)(void) 1> ] 1>e:\dev\trunk\clients\kirit saelensminde\samples\boost cookbook\worker thread\worker thread.cpp(209) : error C2893: Failed to specialize function template 'boost::shared_ptr> Worker::operator ()(F)' 1> With the following template arguments: 1> 'int (__cdecl *)(void)' Is this a dependant type problem stopping the remove_pointer from working? K