Re: [preprocessor] increase tuple size

From: Edward Diener (eldiener_at_[hidden])
Date: 2019-10-23 18:35:15

On 10/23/2019 2:16 AM, Gavin Lambert via Boost-users wrote:
> On 23/10/2019 09:41, pavel b wrote:
>> preprocessor/config/limits.hpp limits tuple size to 64 elements. 
>> Changing the BOOST_PP_LIMIT_TUPLE in this file seems not to have any 
>> effect. Is it possible to increase the maximal tuple size?
> 
> If you can use a modern compiler that supports variadic macros (thus 
> BOOST_PP_VARIADICS=1), then AFAIK it should support any size (up to 
> whatever your compiler's limit is).
> 
> This may require telling your compiler to compile in C++11 or later mode.
> 
> Alternatively you can try forcing it on by #define BOOST_PP_VARIADICS 1 
> before including any Boost headers (in all translation units), but this 
> is less preferable.
> 
> https://www.boost.org/doc/libs/1_68_0/libs/preprocessor/doc/topics/variadic_macros.html 

No, this is not true. The current design in the Boost preprocessor 
library does not allow the user to change the limits and therefore get 
more elements supported of any of the Boost PP data types. Whether a 
compiler supports variadic macros or not makes no difference with the 
current code. Please remember that all the design of the Boost PP data 
types, by Paul Mensonides, was done before variadic macros even existed. 
Anyone who believes they can change the current design to something 
better, which would allow arbitrary numbers of elements for any of the 
Boost PP data types, such as the tuple, is free to submit a PR to do so.