129. Composition

Question.2

Two developers model a GPS module that uses UART:

Developer A -- Inheritance:

class GPS : public UART { /* GPS is-a UART? */ };

Developer B -- Composition:

class GPS {
   UART& uart;  // GPS has-a UART
public:
   GPS(UART& u) : uart(u) {}
};

Which is better embedded C++ practice?

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Developer A -- inheritance is always preferred in OOP
Developer A -- inheritance gives GPS all UART methods automatically
Developer B -- GPS is not a UART; it uses a UART for communication. Composition correctly models this relationship and allows swapping the transport
Both are equivalent

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