Re: [Boost-users] [preprocessor] variable repetition

Subject: Re: [Boost-users] [preprocessor] variable repetition
From: Manfred Doudar (manfred.doudar_at_[hidden])
Date: 2010-05-31 06:59:26

Hello,

I find I am still far from a solution to this, and hope someone might
kindly chime in.  At the _bottom_ of this email is what I've got so far,
though falls short of a solution...  help is still sorely needed.

> Not having a good time with the PP lately, and am struggling over the
> following - would like to generate:
> 
> 
>     void foo(T1)
>     {
>          bar<T1>(a[0]);
>     }
> 
>     void foo(T1, T2)
>     {
>         bar<T1, T2>(a[0]);
>         bar<T1, T2>(a[1]);
>     }
> 
>     void foo(T1, T2, T3)
>     {
>         bar<T1, T2, T3>(a[0]);
>         bar<T1, T2, T3>(a[1]);
>         bar<T1, T2, T3>(a[2]);
>     }
> 
>  ...and so on.

I have this far:

#define <boost/preprocessor/iteration/local.hpp>
#define <boost/preprocessor/iteration.hpp>
#define <boost/preprocessor/repetition.hpp>
#define <boost/preprocessor/repetition/enum.hpp>
#define <boost/preprocessor/repetition/enum_params.hpp>
#define <boost/preprocessor/repetition/repeat.h>

#define PASTE(z, n, T)  T ## n
/**/

#define MACRO(z, n, T)  bar<BOOST_PP_REPEAT(n, PASTE, T)> (a[n]);
/**/

#define INIT(z, n, T)   BOOST_PP_REPEAT(1, MACRO, T)
/**/

#define OP2(z, n, T)                               \
                                                   \
    void foo(BOOST_PP_ENUM_PARAMSi(n, T))          \
    {                                              \
        BOOST_PP_REPEAT(n, INIT, T)                \
    }
    /**/

#define OPERATOR(z, n, _)  OP2(z, n, T)

#define BOOST_PP_LOCAL_MACRO(n) OPERATOR(_, n, _)
#define BOOST_PP_LOCAL_LIMITS(1, 3)
#include BOOST_PP_LOCAL_ITERATE()
#undef BOOST_PP_LOCAL_MACRO
#undef BOOST_PP_LOCAL_LIMITS
#undef OPERATOR

The above almost gives what I am after, **but fails**; resulting output
is:

   void foo(T0)
   {
        bar< >(a[0]);
   }
   void foo(T1, T2)
   {
        bar< >(a[0]);
        bar< >(a[0]);
   }
   void foo(T1, T2, T3)
   {
        bar< >(a[0]);
        bar< >(a[0]);
        bar< >(a[0]);
   }

-template parameters on 'bar' are still  lacking
-varying index on 'a' also lacking

..Sincerely hoping a kind soul might point out what in the above needs
changing to achieve desired result.

--
Manfred