Just a thought on the filesystem implementation. Why not separate the path from the filesystem? Let the path be a container for all kind of paths that follow the generic syntax explained in the boost::filesystem documentation. Then use implementation classes that handles root name and conversion to native strings etc. The benefits would be: 1. The path can be used for other things than filesystems (XPath, Win32 registry) 2. Operations can be implemented selectivly for different types (No need for the current messy #ifdefs) bool exists( const path_base<posixfs<std::string> >& aPath); bool exists( const path_base<win32fs<std::wstring> >& aPath); bool exists( const path_base<win32reg<boost::fixed_string<100> > >& aPath); 3. Easy to expand the functionality for specific tasks without touching the boost headers. The implementation could look something like: template <class ImplT> class path_base : private ImplT { public: typedef ImplT::string_type string_type; path_base() : ImplT() {} // all path operations as in current implementation ... private: string_type m_path; }; // // implementation for win32 filesystem // template <class StringT> class win32fs { // root-name ::= root-drive | root-share | root-device // root-drive ::= char ":" // root-share ::= "//" name // root-device ::= name ":" protected: typedef StringT string_type; win32fs() { } string_type make_generic(const string_type::value_type* src); string_type native_file_string(const string_type& m_path) const { return algorithm::replace_all_copy(m_root + m_path, "/", "\\"); } ... private: string_type m_root }; // // implementation of posix filesystem // template <class StringT> class posixfs { win32fs() { } string_type make_generic(const string_type::value_type* src); string_type native_file_string(const string_type& m_path) const { return m_path; } ... } #ifdef BOOST_POSIX typedef path_base<posixfs<std::string>> path; #else ...