[boost] [typeof] preprocessor reentrancy

From: Cromwell Enage (sponage_at_[hidden])
Date: 2006-01-13 14:59:56

Reposting under a new subject.

--- Arkadiy Vertleyb wrote:
> I think you may want to use (BOOST_PP_)REPEAT in
conjunction
> with SEQ_ELEM and SEQ_SIZE instead of SEQ_FOR_EACH. 
Since
> REPEAT is automatically re-entrant, it may be less
trouble to
> use it, and you don't depend on what typeof has
inside.

I'm also studying file iteration so I can see if that
helps me out.

> (OTOH, I am thinking of adopting the same strategy,
so that
> people don't have re-entrancy problems when using
typeof.)

Please do adopt this strategy.  Currently this kind of
code doesn't work:

BOOST_TYPEOF_REGISTER_TYPE(
    boost::mpl::math::string_c_to_double
  , BOOST_MPL_PP_ARG_SEQ(unsigned char, 40)
)

BOOST_MPL_PP_ARG_SEQ uses BOOST_PP_REPEAT to create a
sequence of N elements containing the specified
primitive integral type.

> Added in CVS:
> 
> BOOST_TYPEOF_REGISTER_TYPE_EXPLICIT_ID(Name, Id)
> BOOST_TYPEOF_REGISTER_TEMPLATE_EXPLICIT_ID(Name,
Params, Id)

I'll make use of them when I get the chance.

                              Cromwell D. Enage

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