class.cpp

class Adaptee {
public:
    void specificRequest();
};

class Target {
public:
    virtual void request() = 0;
};

class Adapter : public Target, Adaptee {
public:
    Adapter()
        : Target(), Adaptee()
    {}

    void request() override {
        specificRequest();
    }
};

object.cpp

class Adaptee {
public:
    void specificRequest();
};

class Target {
public:
    virtual void request() = 0;
};

class Adapter : public Target {
public:
    void request() override {
        adaptee.specificRequest();
    }

private:
    Adaptee adaptee;
};