DP: Adapter

The Adapter allows incompatible interfaces to work together. It acts as a wrapper that converts one interface into another expected by the client.

This is extremely common in embedded systems when integrating legacy drivers, third-party libraries, or hardware modules with different APIs.

  • Integrates old and new systems
  • Reuses legacy code without modification

C Example

c 
#include <stdio.h>

// Existing driver
void legacySend(char* msg) {
    printf("Legacy send: %s\n", msg);
}

// Desired interface
typedef struct {
    void (*send)(const char*);
} UART;

// Adapter
void adapterSend(const char* msg) {
    legacySend((char*)msg);
}

UART getUARTAdapter() {
    UART u;
    u.send = adapterSend;
    return u;
}

int main() {
    UART uart = getUARTAdapter();
    uart.send("Hello");
}

C++ Example

cpp 
#include <iostream>
using namespace std;

class LegacyUART {
public:
    void sendData(string msg) {
        cout << "Legacy: " << msg << endl;
    }
};

class UART {
public:
    virtual void send(string msg) = 0;
};

class UARTAdapter : public UART {
    LegacyUART legacy;
public:
    void send(string msg) override {
        legacy.sendData(msg);
    }
};

int main() {
    UART* uart = new UARTAdapter();
    uart->send("Hello");
    delete uart;
}