Re: "Type-safe" sprintf

On Thu, 8 Mar 2007 14:53:29 +0100, Daniel Lidstr?m wrote:


I simplified the implementation a little bit, so that the first argument
fed to cool::sprintf has to be the format string. This is to prevent errors
like:

cool::sprintf(buffer) % 1 % "%d";

already at compile time.

Here's the updated version:

namespace cool
{
   namespace detail
   {
      template<class Char>
      class feeder
      { };

      template<class Char, std::size_t N>
      class feeder<Char[N]>
      {
         typedef typename boost::basic_format<Char> format_type;
         typedef typename std::basic_string<Char> string_type;

         format_type format;
         Char* buffer;

      public:

         feeder(Char* b)
            : buffer(b)
         { }

         ~feeder()
         {
            string_type result = str(format);
            if( result.size()>=N )
               throw std::logic_error("buffer overflow in sprintf");
            std::copy(result.begin(), result.end(), buffer);
            buffer[result.size()] = 0;
         }

         //! Format string
         format_type& operator%(const Char* c)
         {
            format.parse(c);

            return format;
         }
      };
   }

   template<class Source>
   typename detail::feeder<Source> sprintf(Source& buffer)
   {
      typedef typename detail::feeder<Source> Feeder;
      return Feeder(buffer);
   }
}

--
Daniel
A: Because it messes up the order in which people normally read text.
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