Re: [boost] Preprocessor directive for a sequence that differs only in datatype

On 11/07/2017 19:22, Rishabh Arora wrote:

I was trying to use the boost.preprocessor to write some code which otherwise needs to be written for all the cases. Here's the code: https://github.com/BoostGSoC17/dataframe/blob/master/include/df.cpp (line no. 430 and 431). But on compilation it gives the error: error: macro "BOOST_PP_SEQ_ELEM_III" requires 2 arguments, but only 1 given print_column (i);

I didn't understand the reason as when I wrote: print_column (i); it works fine. Can anyone help me understand the error or provide an alternative way to do the same thing?

BOOST_PP_SEQ_ELEM's first parameter must be an expression resolvable at preprocessing time (usually a constant). "type" doesn't exist until runtime.