2026-05-16 (3UE*2): Exercise Polymorphic Types#

  • Based on the demo in 2026-05-11 (3VO): C++: Inheritance (Mocking A Sensor), rearrange the PMWPin side of Logic in a way that:

    • PWMPin constitutes an interface

    • The original PWMPin concrete implementation is renamed to LinuxSysfsPWMPin

    • LinuxSysfsPWMPin implements the PWMPin interface

    • Logic uses the interface, PWMPin

  • Modify main.cpp in a way that the “real” hardware implementations LinuxSysfsPWMPin and LinuxHWMONSensor are not instantiated.

    Rather, instantiate MockSensor and StdoutPWMPin, and pass these to Logic. When everything is well, you should see whatever you wrote in your StdoutPWMPin implementation.

@startuml interface Sensor { + double get_temperature() } interface PWMPin { + void set_duty_cycle(uint64_t) + void set_period(uint64_t) } class LinuxSysfsPWMPin {} PWMPin <|.. LinuxSysfsPWMPin class StdoutPWMPin {} PWMPin <|.. StdoutPWMPin note bottom of StdoutPWMPin: writes new period/duty_cycle to std::cout class Logic { + void loop() } Logic -l-> Sensor Logic -r-> PWMPin @enduml