C/C++ Users Group Library 1996 July/C-C++ Users Group Library July 1996.iso/listings/v_12_03/saks/polygon.h

C/C++ Source or Header | 1994-01-12 | 870b | 64 lines

Listing 3 - the shape hierarchy with rectangle and triangle
derived from abstract base class polygon

class shape
    {
public:
    ...
    virtual shape *clone() const = 0;
    ...
    };

...

class circle : public shape
    {
public:
    shape *clone() const;
    ...
    };

shape *circle::clone() const
    {
    return new circle(*this);
    }

...

class polygon : public shape
    {
public:
//  shape *clone() const = 0;   // still pure
    ...
    };

...

class rectangle : public polygon
    {
public:
    shape *clone() const;
    ...
    };

shape *rectangle::clone() const
    {
    return new rectangle(*this);
    }

...

class triangle : public polygon
    {
public:
    shape *clone() const;
    ...
    };

shape *triangle::clone() const
    {
    return new triangle(*this);
    }

...