/**/#include "Geom.H"class Event;#ifdef Implementationclass Image {  public:    virtual void Draw(const Point&);};/**/class Image;extern Image* LoadAnImageFile(const char*);    // external function/**/class ImagePtr {public:    ImagePtr(const char* imageFile);    virtual ~ImagePtr();/**/    virtual Image* operator->();    virtual Image& operator*();private:    Image* LoadImage();private:    Image* _image;    const char* _imageFile;};/**/ImagePtr::ImagePtr (const char* theImageFile) {    _imageFile = theImageFile;    _image = 0;}/**/Image* ImagePtr::LoadImage () {    if (_image == 0) {        _image = LoadAnImageFile(_imageFile);    }    return _image;}/**/Image* ImagePtr::operator-> () {    return LoadImage();}/**/Image& ImagePtr::operator* () {    return *LoadImage();}/**/void dummy () {/**/ImagePtr image = ImagePtr("anImageFileName");image->Draw(Point(50, 100));      // (image.operator->())->Draw(Point(50, 100))/**/}/**/#endif/**/#ifdef SampleCode#include "iostream.h"#include "strings.h"/**/class Graphic {public:    virtual ~Graphic();/**/    virtual void Draw(const Point& at) = 0;    virtual void HandleMouse(Event& event) = 0;/**/    virtual const Point& GetExtent() = 0;/**/    virtual void Load(istream& from) = 0;    virtual void Save(ostream& to) = 0;protected:    Graphic();};/**/class Image : public Graphic {public:    Image(const char* file);  // loads image from a file    virtual ~Image();/**/    virtual void Draw(const Point& at);    virtual void HandleMouse(Event& event);/**/    virtual const Point& GetExtent();/**/    virtual void Load(istream& from);    virtual void Save(ostream& to);private:    // ...};/**/class ImageProxy : public Graphic {public:    ImageProxy(const char* imageFile);    virtual ~ImageProxy();/**/    virtual void Draw(const Point& at);    virtual void HandleMouse(Event& event);/**/    virtual const Point& GetExtent();/**/    virtual void Load(istream& from);    virtual void Save(ostream& to);protected:    Image* GetImage();private:    Image* _image;    Point _extent;    char* _fileName;};/**/ImageProxy::ImageProxy (const char* fileName)  {    _fileName = strdup(fileName);    _extent = Point::Zero;  // don't know extent yet    _image = 0;}Image* ImageProxy::GetImage() {    if (_image == 0) {        _image = new Image(_fileName);    }    return _image;}/**/const Point& ImageProxy::GetExtent () {    if (_extent == Point::Zero) {        _extent = GetImage()->GetExtent();    }    return _extent;}/**/void ImageProxy::Draw (const Point& at) {    GetImage()->Draw(at);}/**/void ImageProxy::HandleMouse (Event& event) {    GetImage()->HandleMouse(event);}/**/void ImageProxy::Save (ostream& to) {    to << _extent << _fileName;}/**/void ImageProxy::Load (istream& from) {    from >> _extent >> _fileName;}/**/class TextDocument {public:    TextDocument();    void Insert(Graphic*);    // ...};/**/void dummy () {/**/TextDocument* text = new TextDocument;// ...text->Insert(new ImageProxy("anImageFileName"));/**/}/**/#endif/**/