Re: [Boost-users] [Preprocessor] how to use REPEAT_FROM_TO for 2 arguments

Subject: Re: [Boost-users] [Preprocessor] how to use REPEAT_FROM_TO for 2 arguments
From: Kai Liu (tjroamer_at_[hidden])
Date: 2010-01-07 01:28:47

Hi Steven,

thanks for your answer. It solves my puzzle.

BR,

/Kenny

2010/1/6 Steven Watanabe <watanabesj_at_[hidden]>

> AMDG
>
>
> Kai Liu wrote:
>
>> I am trying to use the preprocessor library to simplify the code I have.
>>
>> The problem:
>> I have many lines of the following assignments:
>>
>> mybfclass x_0_mybf;
>> mybfclass x_1_mybf;
>> ...
>> mybfclass1 x_0_mybf1;
>> mybfclass1 x_1_mybf1;
>> ...
>> mybfclass2 x_0_mybf2;
>> mybfclass2 x_1_mybf2;
>>
>> then I defined several vectors:
>>
>> vector<mybfclass*> x_mybf;
>> vector<mybfclass1*> x_mybf1;
>> vector<mybfclass2*> x_mybf2;
>> *
>> use the boost preprocessor library, I write the following code:
>>
>> #define* DECLX_mybf(z, n, text) BOOST_PP_CAT(text, BOOST_PP_CAT(_,
>> mybf)).push_back(&BOOST_PP_CAT(text, BOOST_PP_CAT(BOOST_PP_CAT(_, n),
>> BOOST_PP_CAT(_, mybf))));
>> *#define* DECLX_mybf1(z, n, text) BOOST_PP_CAT(text, BOOST_PP_CAT(_,
>> mybf)).push_back(&BOOST_PP_CAT(text, BOOST_PP_CAT(BOOST_PP_CAT(_, n),
>> BOOST_PP_CAT(_, mybf))));
>> *#define* DECLX_mybf2(z, n, text) BOOST_PP_CAT(text, BOOST_PP_CAT(_,
>> mybf)).push_back(&BOOST_PP_CAT(text, BOOST_PP_CAT(BOOST_PP_CAT(_, n),
>> BOOST_PP_CAT(_, mybf))));
>>
>> BOOST_PP_REPEAT_FROM_TO(0, 2, DECLX_mybf, x);
>> *// generated: x_mybf.push_back(&x_0_mybf); x_mybf.push_back(&x_1_mybf);
>> * BOOST_PP_REPEAT_FROM_TO(0, 2, DECLX_mybf1, x);
>> *// generated: x_mybf1.push_back(&x_0_mybf1);
>> x_mybf1.push_back(&x_1_mybf);
>> * BOOST_PP_REPEAT_FROM_TO(0, 2, DECLX_mybf2, x);
>> *// generated: x_mybf2.push_back(&x_0_mybf2);
>> x_mybf2.push_back(&x_1_mybf);
>> *
>> but I think it is too much coding here, since I have to write a macro for
>> each mybf occurrence, DECLX_mybf
>>
>> I have difficulty to use the BOOST_PP_REPEAT_FROM_TO for two argument,
>> since
>> the macro(z, x, data) can only accept one argument data, however, I need
>> to
>> pass two arguments x and mybf to the macro,
>> in order to generate a mybfclass1 x_0_mybf.
>>
>> does anyone know how to apply macro to generate the above structure?
>>
>>
>
> Wrap the arguments in a tuple:
>
> #define DECLX(z, n, data) \
>   BOOST_PP_CAT(\
>       BOOST_PP_TUPLE_ELEM(2, 1, data),\
>       BOOST_PP_CAT(\
>           _,\
>           BOOST_PP_TUPLE_ELEM(2, 0, data))\
>   ).push_back(\
>       &BOOST_PP_CAT(\
>           BOOST_PP_TUPLE_ELEM(2, 1, data),\
>
>           BOOST_PP_CAT(\
>               BOOST_PP_CAT(_, n),\
>               BOOST_PP_CAT(\
>                   _,\
>                   BOOST_PP_TUPLE_ELEM(2, 0, data)))));
>
> BOOST_PP_REPEAT_FROM_TO(0, 2, DECLX, (mybf, x));
>
> In Christ,
> Steven Watanabe
>
>
> _______________________________________________
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> Boost-users_at_[hidden]
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>

-- 
Kai Liu
Wichernstr. 18
91052, Erlangen
MSN: tjroamer_at_[hidden]