shapefactory1.cpp

来自「很经典的书籍」· C++ 代码 · 共 68 行

//: C10:ShapeFactory1.cpp
#include <iostream>
#include <stdexcept>
#include <string>
#include <vector>
#include "../purge.h"
using namespace std;

class Shape {
public:
  virtual void draw() = 0;
  virtual void erase() = 0;
  virtual ~Shape() {}
  class BadShapeCreation : public logic_error {
  public:
    BadShapeCreation(string type)
      : logic_error("Cannot create type " + type)
    {}
  };
  static Shape* factory(const string& type)
    throw(BadShapeCreation);
};

class Circle : public Shape {
  Circle() {} // Private constructor
  friend class Shape;
public:
  void draw() { cout << "Circle::draw\n"; }
  void erase() { cout << "Circle::erase\n"; }
  ~Circle() { cout << "Circle::~Circle\n"; }
};

class Square : public Shape {
  Square() {}
  friend class Shape;
public:
  void draw() { cout << "Square::draw\n"; }
  void erase() { cout << "Square::erase\n"; }
  ~Square() { cout << "Square::~Square\n"; }
};

Shape* Shape::factory(const string& type)
  throw(Shape::BadShapeCreation) {
  if(type == "Circle") return new Circle;
  if(type == "Square") return new Square;
  throw BadShapeCreation(type);
}

char* shlist[] = { "Circle", "Square", "Square",
  "Circle", "Circle", "Circle", "Square", "" };

int main() {
  vector<Shape*> shapes;
  try {
    for(char** cp = shlist; **cp; cp++)
      shapes.push_back(Shape::factory(*cp));
  } catch(Shape::BadShapeCreation e) {
    cout << e.what() << endl;
    purge(shapes);
    return 1;
  }
  for(size_t i = 0; i < shapes.size(); i++) {
    shapes[i]->draw();
    shapes[i]->erase();
  }
  purge(shapes);
} ///:~