Re: namespace vs static member functions

From: (Carl Barron)
Sat, 31 Mar 2007 00:27:27 CST
Drew Hall <> wrote:

On Mar 27, 5:38 pm, Carl Barron <> wrote:

Another differences that there are templated classes/structs and there
are no templated namespaces. This could be the decider in many

No, but there are template functions within a namespace.
At some level there's not much difference between:




That said, I definitely lean towards using a namespace for reasons
others have mentioned...


  It all depends on if you want large conditional compilation segmenets
or simple ones.

   namespace endian_stuff
       template <int N1,int N2,int N3,int N4>
       struct swapper
         static void swap_bytes(unsigned char *,unsigned char *);
         static void un_swap_bytes(unsigned char *,unsigned char *);

       template <bool Castable>
       struct chooser
         static const int value = (sizeof(unsigned long <=4)
                                 ?sizeof(unsigned long):0;

       teemplate <> struct chooser<false>
       { static const int value = 0;};

       template<int N1,int N2,int N3,int N4,int S> struct selection;
       template <int N1,int N2,int N3,int N4>
         struct selection<N1,N2,N3,N4,1>{};
      // same for last parameter = 2 and 3.
       template <int N1,int N2,int N3,int N4
         struct selection<N1,N2,N3,N4,0>:private swapper<N1,N2,N3,N4>
           // separate into unchar's via arithmetic.
           static unsigned long encode(unsigned long);
           static unsigned long decode(Unsigene long);
         // sizeof(unsigned long == 4 and casting works
         template <int N1,int N2,int N3,int N4.4>
         struct selection<N1,N2,N3,N4,4>:private swapper<N1,N2,N3,N4>
          // impliment encode and decode using casts.
          static unsigned long encode(unsigned long);
          static unsigned long decode(unsigned long);


   template <Int N1,int N2,int N3,int N4,bool Castable = true>
   struct basic_endian:endian stuff::selection

noe single typedef of the form
    typedef basic_endian<...> endian;
   is all that is needed to be conditionally compiled. and the proper
encoding and decoding procedures will be compiled. If 1 <=
sizeof(unsigned long) <= 3 the compilation will fail.
endian_stuff::selection will then not have proprer functions declared.
still assumes CHAR_BIT == 8, in the full coded version. Using just
namespaces and template functions alone. is a lot messier, if only the
function is to be selected at compile time.

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