getenv.hpp

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#pragma once
 
#include <sstream>
#include <stdlib.h>
#include <vector>
 
namespace iganet::utils {
 
template <typename T> T getenv(std::string variable, const T &default_value) {
 
  char *env_value = std::getenv(variable.c_str());
  if (env_value != nullptr)
    if constexpr (std::is_integral_v<T>)
      return static_cast<T>(std::atoll(env_value));
    else if constexpr (std::is_floating_point_v<T>)
      return static_cast<T>(std::atof(env_value));
    else
      return static_cast<T>(env_value);
  else
    return default_value;
}
 
template <typename T>
std::vector<T> getenv(std::string variable,
                      std::initializer_list<T> default_value) {
 
  char *env_value = std::getenv(variable.c_str());
  if (env_value != nullptr) {
    std::stringstream ss(env_value);
    std::vector<T> result;
    std::string item;
 
    if constexpr (std::is_integral_v<T>)
      while (std::getline(ss, item, ','))
        result.emplace_back(static_cast<T>(std::atoll(item.c_str())));
    else if constexpr (std::is_floating_point_v<T>)
      while (std::getline(ss, item, ','))
        result.emplace_back(static_cast<T>(std::atof(item.c_str())));
    else
      while (std::getline(ss, item, ','))
        result.emplace_back(static_cast<T>(item));
    return result;
  } else
    return std::vector<T>{default_value};
}
 
} // namespace iganet::utils