c++ - BOOST_PP_REPEAT with array -

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i have struct :

struct e1 {     typedef boost::tuple<        boost::optional< n::type_a >, // n - namespace      boost::optional< n::type_b >,      ...................      boost::optional< n::type_x > //arbitrary number of, maximal 7      > data_type;      // access name     boost::optional<n::type_a> const&  type_a() const { return boost::get<0>(data); }    boost::optional<n::type_b> const&  type_b() const { return boost::get<1>(data); }    .....................................    boost::optional<n::type_x> const&  type_x() const { return boost::get<2>(data); }     data_type data; };

q: how may create structure using boost preprocessors? me known type_a, type_b, ..., type_x name of types.

it's need me, because must create lot of structures that, changing type_a, type_b, ... types.

in common case, can use boost preprocessor array or set?

you this:

#define types (type_a)(type_b)(type_x)   #define generate_tuple(mar, manamespace, maindex, matype) \   boost_pp_comma_if(maindex) boost::optional<manamespace :: matype>   #define generate_getter(mar, manamespace, maindex, matype) \   boost::optional<manamespace :: matype> const& matype () const { return boost::get<maindex>(data); }   struct e1 {   typedef boost::tuple<     boost_pp_seq_for_each_i(generate_tuple, n, types)   > data_type;    boost_pp_seq_for_each_i(generate_getter, n, types)    data_type data; };

the n argument corresponds manamespace parameter. can of course use argument in other way (it's passed through verbatim), such hardcoding n macros (and passing dummy in argument), or encoding identifier data in there, etc.


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