Steven Burns <royalstream <at> hotmail.com> writes:
Recently I came up with a modified version of boost::array that supports runtime sized arrays....boost::array<int> darray(10);
Something I think would be useful is an implementation similar to std::vector that uses a small-string like optimization, where the size of the stack buffer is a template parameter. For example, myarray<char, 10> v; // allocates 10 bytes on the stack for(int n=0; n<9; n++) v.push_back('.'); // no heap allocations for(int n=0; n<9; n++) v.push_back('.'); // triggers realloc from heap This has a few advantages: (1) For <= 10 chars, it requires no heap allocation and therefore is fast for some things (similar to C arrays and boost::array). (2) It can grow beyond 10 chars via heap allocation (like std::vector but unlike boost::array). (3) It maintains both variable size and capacity (like std::vector but unlike boost::array). In fact, this is the approach I'm taking to reimplement basic_string via flex_string (http://erdani.org/code/main.html), though I had patch flex_string so that it would work with N > 127 : template <size_t N> struct sstring { typedef flex_string< char, std::char_traits<char>, std::allocator<char>, SmallStringOpt<SimpleStringStorage<char>, N> > type; }; sstring<500>::type s; // usage Perhaps there could be a "flex_vector" as well? flex_vector< int, std::allocator<int>, SmallVectorOpt<SimpleVectorStorage<int>, N>
BTW, is there any chance that flex_string might be added to Boost? I see a forked version of it included as a utility in Boost Wave, but it's not a formal part of Boost itself, and it would be nice to have a single version of it maintained. --davidm