Re: [boost] Need for BOOST_PP_VARIADIC_POP_FRONT

Subject: Re: [boost] Need for BOOST_PP_VARIADIC_POP_FRONT
From: Edward Diener (eldiener_at_[hidden])
Date: 2011-11-13 12:04:17

On 11/13/2011 11:05 AM, Gennadiy Rozental wrote:
> Paul Mensonides<pmenso57<at>  comcast.net>  writes:
>
>>
>> Variadic data is not a true data structure and should not be supported as
>> such.  Therefore, it should not have a POP_FRONT, for example.  Convert it
>> into a real data structure (such as a sequence) and then do your
>> processing on that data structure.
>
> How would it help me if I want to take first arguments from __VA_ARGS__ and pass
> the rest to the different variadic macro?

First I would say that it would be better internally to pass a PP 
sequence to your different macro rather than variadic data.

But if you want to do it the way you say above, just convert the 
variadic data to a PP sequnce using BOOST_PP_VARIADIC_TO_SEQ, pop the 
first element from the sequence using BOOST_PP_SEQ_POP_FRONT, convert 
the sequence back to variadic data using BOOST_PP_SEQ_ENUM, and pass 
that data as your variadic data.

In my VMD library and the work I did with Paul in adding variadic data 
to the preprocessor code on the trunk, I always mentioned that I viewed 
C++ variadic data as an easier to use interface for end-users but that 
Boost PP has much richer data types internally. That is why I believe 
the functionality regarding variadic data should be limited because 
Boost PP already has much richer functionality for its data types.

Eddie