cpp/CPPlusV6/Chapter 14/workermi.h

// workermi.h  -- working classes with MI
#ifndef WORKERMI_H_
#define WORKERMI_H_

#include <string>

class Worker   // an abstract base class
{
private:
    std::string fullname;
    long id;
protected:
    virtual void Data() const;
    virtual void Get();
public:
    Worker() : fullname("no one"), id(0L) {}
    Worker(const std::string & s, long n)
            : fullname(s), id(n) {}
    virtual ~Worker() = 0; // pure virtual function
    virtual void Set() = 0;
    virtual void Show() const = 0;
};

class Waiter : virtual public Worker
{
private:
    int panache;
protected:
    void Data() const;
    void Get();
public:
    Waiter() : Worker(), panache(0) {}
    Waiter(const std::string & s, long n, int p = 0)
            : Worker(s, n), panache(p) {}
    Waiter(const Worker & wk, int p = 0)
            : Worker(wk), panache(p) {}
    void Set();
    void Show() const;
};

class Singer : virtual public Worker
{
protected:
enum {other, alto, contralto, soprano,
                    bass, baritone, tenor};
    enum {Vtypes = 7};
    void Data() const;
    void Get();
private:
    static char *pv[Vtypes];    // string equivs of voice types
    int voice;
public:
    Singer() : Worker(), voice(other) {}
    Singer(const std::string & s, long n, int v = other)
            : Worker(s, n), voice(v) {}
    Singer(const Worker & wk, int v = other)
            : Worker(wk), voice(v) {}
    void Set();
    void Show() const;
};

// multiple inheritance
class SingingWaiter : public Singer, public Waiter
{
protected:
    void Data() const;
    void Get();
public:
    SingingWaiter()  {}
    SingingWaiter(const std::string & s, long n, int p = 0,
                            int v = other)
            : Worker(s,n), Waiter(s, n, p), Singer(s, n, v) {}
    SingingWaiter(const Worker & wk, int p = 0, int v = other)
            : Worker(wk), Waiter(wk,p), Singer(wk,v) {}
    SingingWaiter(const Waiter & wt, int v = other)
            : Worker(wt),Waiter(wt), Singer(wt,v) {}
    SingingWaiter(const Singer & wt, int p = 0)
            : Worker(wt),Waiter(wt,p), Singer(wt) {}
    void Set();
    void Show() const; 
};

#endif