Method DeltaRange

examples/custom_validator.cpp:16–27

    T center_point;
    T delta;
    DeltaRange(const T &center, const T &range)
        : CLI::Validator(
              [this](const std::string &value) -> std::string {
                  T newValue;
                  auto result = CLI::detail::lexical_cast(value, newValue);
                  if(!(result && this->check(newValue))) {
                      return std::string("value not within range");
                  }
                  return std::string{};
              },
              "RANGE"),
          center_point(center), delta(range) {}

    CLI11_NODISCARD bool check(const T &test) const {
        return (test >= (center_point - delta)) && (test <= (center_point + delta));