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From: Tobias Schwinger (tschwinger_at_[hidden])
Date: 2005-03-03 14:06:25

Paul Mensonides wrote:
>>-----Original Message-----
>>From: boost-bounces_at_[hidden]
>>[mailto:boost-bounces_at_[hidden]] On Behalf Of Tobias Schwinger
>>Thank you for this very detailed reply !
>>Is it safe to use BOOST_PP_EMTPY or
>>BOOST_PP_INDENTITY(somthing) as the element and "dereference"
>>with '()' ?
> Sure, provided that the result is never "bound" to an argument by itself. E.g.
> #define A(x) B(x)
> #define B(x) x
> A() // undefined: empty argument to A
> A( BOOST_PP_EMPTY() ) // undefined: empty argument to B
> A( BOOST_PP_EMPTY )() // okay

This is about what I meant (well, BOOST_PP_SEQ_ELEM(x,s)() - x being the
index of the "optional element" in a sequence). But according to the
source of SEQ_ELEM this should work as well.

Thanx, again.



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