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copied!<p>Judging from your comment, what you mentioned can be implemented probably by making a predicate class which determines whether the specified class has the member function, and using <code>fusion::filter_view</code>. <code>DEF_HAS_MEM_FUNC</code> macro in the following code is explained at:</p> <p><a href="https://stackoverflow.com/questions/257288/is-it-possible-to-write-a-c-template-to-check-for-a-functions-existence/264088#264088">Is it possible to write a template to check for a function's existence?</a></p> <pre><code>#include <boost/fusion/include/cons.hpp> #include <boost/fusion/include/filter_view.hpp> #include <boost/fusion/include/for_each.hpp> #include <boost/mpl/placeholders.hpp> using namespace boost; #define DEF_HAS_MEM_FUNC( name, func_name, signature ) \ template< class T > \ struct name { \ template< class U, U > struct mfp; \ \ template< class U > \ static char f( mfp< signature, &U::func_name >* ); \ \ template< class > static char (&f(...))[2]; \ \ enum { value = (sizeof( f<T>(0) ) == 1) }; \ } DEF_HAS_MEM_FUNC( has_f, f, void(U::*)()const ); struct DoSomething { template< class U > void operator()( U& u ) const { u.f(); } }; struct A {}; struct B { void f() const {} }; typedef fusion::cons< A, fusion::cons< B > > MyTuple; int main() { MyTuple tuple_; fusion::filter_view< MyTuple const, has_f< mpl::_ > > v( tuple_ ); fusion::for_each( v, DoSomething() ); } </code></pre>

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