Design Patterns Explained

Supplement: C++ Code Examples
Example 9-4 C++ Code Fragments: Rectangles Only
void Rectangle::draw () {
drawLine(_x1,_y1,_x2,_y1);
drawLine(_x2,_y1,_x2,_y2);
drawLine(_x2,_y2,_x1,_y2);
drawLine(_x1,_y2,_x1,_y1);
}
void V1Rectangle::drawLine
(double x1, double y1,
double x2, double y2) {
DP1.draw_a_line(x1,y1,x2,y2);
}
void V2Rectangle::drawLine
(double x1, double y1,
double x2, double y2) {
DP2.drawline(x1,x2,y1,y2);
}
Example 9-5 C++ Code Fragments:
Rectangles and Circles without Bridge
class Shape {
public: void draw ()=0;
}
class Rectangle : Shape {
public:
void draw();
protected:
void drawLine(
double x1,y1, x2,y2)=0;
}
void Rectangle::draw () {
drawLine(_x1,_y1,_x2,_y1);
drawLine(_x2,_y1,_x2,_y2);
drawLine(_x2,_y2,_x1,_y2);
drawLine(_x1,_y2,_x1,_y1);
}
Chapter 9 The Bridge Pattern 157
(continued)