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From: Daniel Wallin (daniel_at_[hidden])
Date: 2008-05-27 15:31:55

Brook Milligan wrote:
> I am trying to use Boost.Parameter to construct some objects, much
> like make_tuple(A,B) does except with some of the arguments being
> optional and replaced by defaults (which may depend on the other
> arguments). The return type, however, must be a template class with
> the template arguments dependent on the arguments supplied.
> Is this possible?

Yes, this is possible. The argument pack is available to the return type
computation as `Args`. Something like this should work:

       (typename boost::parameter::value_type<Args, tag::x>::type),

This only work on trunk unfortunately and since it's not very well
covered in the test suite there might be problems with it.


Daniel Wallin
Boost Consulting

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