Dear Boost community, do we have a function object template to wrap arbitrary constructor calls / operator new expressions somewhere in Boost, already? If not, is there any interest in such a thing? Interface draft: ================ factory<T> // constructs X and returns it by value factory<T*> // uses operator new, returns a pointer Where operator() takes a variable number of arguments, forwarded to the constructor. Should there be an optional 'Allocator' template parameter? Some use cases: =============== o Transform through an explicit constructor, e.g: std::transform(from,to,out,factory<X>()); or a constructor that takes more than one argument, e.g: std::transform(from,to,out, boost::bind(factory<Y>(),12,_1)); o Generate data, e.g: std::generate_n(out,12,boost::bind(factory<Y>(),123,12)); o Creating homogeneous, polymorphic factories from heterogeneous constructors, e.g: void register_factory( std::type_info const &, boost::function<void*()> const &); // ... at function scope: register_factory( typeid(X), factory<X>() ); register_factory( typeid(Y), boost::bind(factory<Y>(),12,1) ); Implementation notes regarding the Forwarding Problem: ====================================================== For now (C++89) it might be good enough to just have operator() take its arguments by non-const reference. As usually the call will be deferred and as long as the arguments are L-Values they will be deduced even if const qualified (this might break the code of the first use case above - wrapping the factory specialization into a Boost.Bind function object without actually binding anything will work around the problem, though). Alternatively we could solve the forwarding problem (within the function object itself) using a "hammer and crowbar utility" in Fusion (overloading operator() with all combinations of templatized const/non-const reference parameters) until we have better means to do so. I personally prefer the former because it's more lightweight and might allow us to be more portable than Fusion is, however. Curiously awaiting your feedback, Tobias