Sorry to start with a negative review: What is your evaluation of the design? -------------------------------------- In the introduction it says "The boost::fixed_string class is aimed at solving the problem outlined above and is designed to be a direct replacement for character buffers, operating as a fixed-capacity string." ("problem above" is buffer overrun and null termination of c-strings) With this in mind I think the fixed_string design is very complicated. Where in the aim does the need for a fixed_string_impl class and a configurable format_policy arise? The more obvious "overrun_policy" isn't in the design. I also don't like the fixed_string_base class. Deriving fixed_string from fixed_string_base means: 1. all fixed_strings have an overhead of 1 pointer and 2 size_t. 2. all operations on fixed_string use one extra pointer indirection. 3. fixed_string can't be used in shared_memory or binary serialization. I think it would be better with a separate fixed_string_ext friend class that works on an external buffer. template <typename CharT> struct basic_fixed_string_ext { template <size_t N> basic_fixed_string_ext(const fixed_string<CharT, N>& f) : buffer_(f.buffer()), capacity(N), size_(f.len) { }; public: CharT* const buffer_; const size_t capacity_; size_t& size_; }; I also miss a few things: - operations/construction with basic_string or boost::range - Easier way to handle length. Currently it is easy to forget to update the length after using buffer(). Most of my code looks like fstr.setlength(apifunc(fstr.buffer())); or apifunc(fstr.buffer()); fstr.setlength() The solution is probably to either: * Don't store the length * let buffer() invalidate the length and update it when needed. * let buffer() return a proxy that sets the length when destroyed. - fixed_stringstream. What is your evaluation of the documentation? ----------------------------- The documentation looks good but I think it is done the wrong way. The main interface class "fixed_string" is deep inside the design page and only got 2 lines of documentation. "This is the main class that provides the fixed-capacity string implementation, deriving itself from boost::fixed_string_base. It also provides the constructors specified in the std::basic_string interface." You need to look in the documentation for fixed_string_base to find out that fixed_string got the full basic_string interface plus a few more functions. What is your evaluation of the potential usefulness of the library? ----------------------------- Could be useful in applications where you want to avoid dynamic memory allocations but I don't find it useful for char array replacement. It is just to much trouble with setlength and conversion to/from basic_string. Did you try to use the library? With what compiler? Did you have any problems? ----------------------------- I am currently using an earlier version (December 2004). The review version doesn't work for me on VC70. boost\fixed_string\fixed_string.hpp(400) : error C2065: 'recalc_' : undeclared identifier Please always state in your review, whether you think the library should be accepted as a Boost library! ----------------------------- I vote No.