Re: [boost] tuple<T,T,...> generator meta-function

Subject: Re: [boost] tuple<T,T,...> generator meta-function
From: mbiddeg_at_[hidden]
Date: 2009-10-23 10:13:55

Both will work, if you want different types generated.

I think Emre wants the same type generated for T, not T0, T1, T2..... as the preprocessor & variadics would do.

Pass make_tuple<int, 8>, & it generates a tuple of 8 ints.

However, if otherwise, & no access to C++ 0x:

#include <boost/preprocessor/repetition/enum_params.hpp>

template<size_t VAL, size_t LIMIT>

 struct limit_repeat {

    enum { value = LIMIT < VAL ? LIMIT : VAL };

};

template <typename T, size_t N, size_t M>

struct make_tuple { };

 template <typename T>

 struct make_tuple<T, N = 1,  M = limit_repeat<N, BOOST_PP_LIMIT_REPEAT>::value >

 {

      typedef boost::tuple<BOOST_PP_ENUM_PARAMS(M, T)> type;

  };

______________________________________________________________________

Kizza George Mbidde

Interconnect Billing Systems Analyst

IT

cell: [phone]

email: mbiddeg_at_[hidden]

-----Original Message-----
From: boost-bounces_at_[hidden] [mailto:boost-bounces_at_[hidden]] On Behalf Of Frank Mori Hess
Sent: October 23, 2009 16:16
To: boost_at_[hidden]
Subject: Re: [boost] tuple<T,T,...> generator meta-function

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Hash: SHA1

On Friday 23 October 2009, Emre Turkay wrote:

> Hi folks,

>

> How can I do this in a better way?

>

>     template <typename T, size_t N>

>     struct make_tuple { };

>

>     template <typename T>

>     struct make_tuple<T, 1>

>     {

>         typedef boost::tuple<T> type;

>     };

>

>     template <typename T>

>     struct make_tuple<T, 2>

>     {

>         typedef boost::tuple<T, T> type;

>     };

>

If you have a c++0x compiler, you could define it recursively using variadic

templates.  Otherwise, you could use Boost.Preprocessor.

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