Drill 23: Change a value — Exceptions and safety

#include <fstream>
#include <iostream>
#include <stdexcept>
#include <string>

class NotesFile {
public:
    explicit NotesFile(const std::string& path) : file_(path) {
        if (!file_.is_open()) {
            throw std::runtime_error("cannot open " + path);
        }
    }

    std::string read_line() {
        std::string line;
        if (!std::getline(file_, line)) {
            throw std::runtime_error("read failed");
        }
        return line;
    }

private:
    std::ifstream file_;
};

int clamp(int value, int low, int high) noexcept {
    if (value < low) return low;
    if (value > high) return high;
    return value;
}

void load() {
    try {
        NotesFile notes{"notes.txt"};
        std::cout << notes.read_line() << "\n";
    } catch (const std::exception& error) {
        std::cout << "error: " << error.what() << "\n";
    }
}