RAII in modern C++ (example a)

CMakeLists.txt

cmake_minimum_required(VERSION 3.0.0)
project(raii_examples VERSION 0.1.0)

set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_STANDARD_REQUIRED ON)
set(CMAKE_CXX_EXTENSIONS OFF)

add_executable(raii_1 raii_1.cpp)

raii_1.cpp

#include <iostream>
#include <string>
#include <string_view>

struct OpenFile
{
    OpenFile(std::string_view filename)
    {
        std::cout << "Opening the file" << std::endl;
        // file_.exceptions(std::ifstream::failbit | std::ifstream::badbit);
        file_ = fopen(filename.data(), "r");
        if (file_ == NULL) {
            throw std::runtime_error(std::strerror(errno));
        }
    }

    std::string ReadLine()
    {
        char line[255];
        fgets(line, sizeof(line), file_);
        return std::string(line);
    }

    ~OpenFile()
    {
        std::cout << "Closing the file" << std::endl;
        fclose(file_);
    }

private:
    FILE *file_;
};

int main()
{
    try {
        OpenFile my_file{"ssample.txt"};
        std::string line = my_file.ReadLine();
        std::cout << line << std::endl;
    } catch(std::runtime_error& e) {
        std::cerr << e.what() << std::endl;
    }
    
    return 0;
}