Thank you, Gavin Lambert. I don't think any of the preprocessor directives will work then? because type cannot be determined at comile time? Is there any other way to do that?

On 07/11/2017 06:17 AM, Larry Evans via Boost wrote:

On 07/11/2017 03:09 AM, Rishabh Arora via Boost wrote:

...

Thank you, Gavin Lambert. I don't think any of the preprocessor directives will work then? because type cannot be determined at comile time? Is there any other way to do that?

What about replacing the switch with an index into a vector of function pointers? Something like:

#include <iostream> template < class T > void print_column(std::size_t col) { T dummy; std::cout <

More specifically: #ifdef USE_PRINTER_TYPES template struct printers { using fptr = void(data_frame::*)(size_t); static constexpr fptr _[sizeof...(Types)]= { &data_frame::print_column<Types>... }; }; using printer_types=printers; #endif//USE_PRINTER_TYPES Then, use printer_types in the data_frame::print function as: std::cout << "[" << column_headers_(i) << "]" << ": "; auto const itype=base_::operator[](column_headers_(i)).type(); #ifdef USE_PRINTER_TYPES printer_types::fptr printer=printer_types::_[itype]; (this->*printer)(i); #else switch(itype) { . . . #endif//USE_PRINTER_TYPES HTH. -regards, Larry

On Wed, Jul 12, 2017 at 4:47 AM, Gavin Lambert via Boost < boost@lists.boost.org> wrote:

On 11/07/2017 20:09, Rishabh Arora wrote:

...

I don't think any of the preprocessor directives will work then? because type cannot be determined at comile time? Is there any other way to do that?

You might want to look at the Boost.Fusion library ( http://www.boost.org/doc/libs/1_64_0/libs/fusion/doc/html/).

How Can I use boost.fustion library as it requires compile time computations if I am not wrong. Please correct me if I am.

Or if this is C++11+ code, at std::tuple and std::get. Though some of these might still require values known at compile time; depending on your usage you might be able to use constexpr methods for that, however.

Can you please elaborate?

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