online compiler and debugger for c/c++

#include <iostream> #include <string> #include <string_view> // assume you have a bit of code that needs to log something // In this example I made a temperature sensor that needs to do some logging // but the temperature sensor doesn't want to know anything about the logging system // In that case make an interface that allows your temperature sensor to report something. class temparature_sensor_report_itf { public: virtual ~temparature_sensor_report_itf() = default; virtual void report_temparature(int temp) = 0; virtual void report_too_hot() = 0; }; // Now you can write your code to use this interface class logger_t { public: // The initialization of the logger is to be done // using a constructor explicit logger_t(std::string_view filename) : m_filename{filename} { } void log(std::string_view msg) { std::cout << "Logging: " << msg << "\n"; } private: std::string m_filename; }; // now make an adapter from report_itf to a specific logger_t // this allows you to change the logger_t without changing the // code that uses the temparature_sensor_report_itf (the temperature sensor class) class temparature_sensor_logger_t : public temparature_sensor_report_itf { public: temparature_sensor_logger_t(logger_t& logger) : m_logger{logger} { } void report_temparature(int temp) override { m_logger.log("Temperature: " + std::to_string(temp)); } void report_too_hot() override { m_logger.log("Too hot!"); } private: logger_t& m_logger; }; // For unit testing you can now also make a reporter class that does nothing at all class temperature_sensor_report_nothing_t : public temparature_sensor_report_itf { public: void report_temparature(int temp) override { // do nothing } void report_too_hot() override { // do nothing } }; // The temperature sensor class doesn't know anything about the logger // it only has an injected dependency to the temparature_sensor_report_itf class temparature_sensor_t { public: explicit temparature_sensor_t(temparature_sensor_report_itf& reporter) : m_sensor_reporter{reporter} { } void read_temparature() { // read the temperature int temp = 42; // report the temperature // but you don't know anything about the logger here. m_sensor_reporter.report_temparature(temp); if (temp > 40) { m_sensor_reporter.report_too_hot(); } } private: temparature_sensor_report_itf& m_sensor_reporter; }; int main() { // do NOT make a global logger initialize your logging system in main // this also allows the destructor of your logger to do nice things // like flushing the log file and closing it (something you cannot do // when you use a singleton with a new but no delete) logger_t logger{"log.txt"}; // now create a small adapter, this adapter allows you to change // the logging infrastructure later without ever needing // to change anything in the temparature_sensor_t class temparature_sensor_logger_t reporter{logger}; // In unit tests you use this line instead of the previous one // And now you can test without for example depending on the filestystem // temperature_sensor_report_nothing_t reporter; // now create the temparature sensor // by injecting a class derived from temparature_sensor_report_itf // For unit testing we will inject the temperature_sensor_report_nothing_t instance temparature_sensor_t sensor{reporter}; // now read the temperature, if something needs to be reported // it will be reported to the logger sensor.read_temparature(); return 0; }