Re: [boost] [relational] Relational Model Library

From: Larry Evans (cppljevans_at_[hidden])
Date: 2005-09-28 16:34:22

On 09/27/2005 03:24 PM, Calum Grant wrote:
[snip]
> Is there any interest in providing relational containers in Boost?  Are
> there any features/improvements you can suggest for RML?
Why not use boost/preprocessor in RM_DEFINE_ROW?  The following
shows it can be used to define at least 2 parts of the struct Name:

<------------- RM_DEFINE_ROW.hpp -------------------
#include <boost/preprocessor/punctuation/comma_if.hpp>
#include <boost/preprocessor/seq/size.hpp>
#include <boost/preprocessor/repetition/repeat.hpp>
#include <boost/preprocessor/seq/elem.hpp>
#include <boost/preprocessor/tuple/elem.hpp>

#define RM_DECL_COL(r,d,tf_pair) \
   BOOST_PP_TUPLE_ELEM(2,0,BOOST_PP_SEQ_ELEM(d,tf_pair)) \
   BOOST_PP_TUPLE_ELEM(2,1,BOOST_PP_SEQ_ELEM(d,tf_pair)); \
   /**/
#define RM_APPEND_TYPE(r,d,tf_pair) \
   BOOST_PP_COMMA_IF(d) \
   BOOST_PP_TUPLE_ELEM(2,0,BOOST_PP_SEQ_ELEM(d,tf_pair)) \
   /**/
#define RM_DEFINE_ROW(Name, type_field_seq) \
   struct Name \
   { \
 
BOOST_PP_REPEAT(BOOST_PP_SEQ_SIZE(type_field_seq),RM_DECL_COL,type_field_seq) 
\
     typedef ::relational::type_list_v< \
 
BOOST_PP_REPEAT(BOOST_PP_SEQ_SIZE(type_field_seq),RM_APPEND_TYPE,type_field_seq) 
\
     > type_list; \
   } \
  /**/

 >---------------------------------------------------
<------------- test.cpp -------------------
#include "RM_DEFINE_ROW.hpp"

RM_DEFINE_ROW(xxx,((int,a_int))((float,a_float)));
 >------------------------------------------
The resulting preprocessor output is:
<------------- code -------------------
struct xxx { int a_int; float a_float; typedef 
::relational::type_list_v< int , float > type_list; };
 >------------- code -------------------