params-concept

This code is a concept implementation of an extremely lightweight parameter parsing library for c++. My main annoyance with other parameter parsing libraries such as boost program options is that they treat the set of command line parameters as dynamic when in almost all cases they are actually statically known. I typically find my code filled with lines such as int parameter = p["parameter_name"].as<int>(); which feels very wasteful since everybody besides the compiler already knowns that the parameter is always an int. This library provides a macro DEFINE_PARAMETER_STRUCT which facilitates parsing command line arguments into a plain structure. It relies on boost::hana for introspection and boost::lexical_cast for conversions.

Installation

All that is needed to use params-concept is to include the single header file params.hpp. params-concept depends on boost, specifically boost::hana and boost:lexical_cast.

Usage

The following short program demonstrates how to use params-concept.

#include "params.hpp"

// takes name and list of tuples of form (type, name, default, help)
DEFINE_PARAMETERS_STRUCT(Parameters, (int, i, 0, "integer"),
                         (std::string, name, "output", "output file"),
                         (bool, help, false, "print help")
                         );

int main(int argc, char *argv[]) {
  Parameters p;

  try {
    parse_params(argc, argv, p);
  } catch (std::exception& e) {
    std::cout << "error: " << e.what() << "\n";
    return -1;
  }

  if (p.help) {
    print_desc(std::cout, p);
    return -1;
  }

  print_values(std::cout, p);

  return 0;
}