Factory is a design pattern in common usage. Implement a ShapeFactory that can generate correct shape.
You can assume that we have only tree different shapes: Triangle, Square and Rectangle.
Example
ShapeFactory sf = new ShapeFactory();
Shape shape = sf.getShape("Square");
shape.draw();
>> ----
>> | |
>> | |
>> ----
shape = sf.getShape("Triangle");
shape.draw();
>> /\
>> / \
>> /____\
shape = sf.getShape("Rectangle");
shape.draw();
这道题让我们求形状工厂，实际上就是Factory pattern的一个典型应用，说得是有一个基类Shape，然后派生出矩形，正方形，和三角形类，每个派生类都有一个draw，重写基类中的draw，然后分别画出派生类中的各自的形状，然后在格式工厂类中提供一个派生类的字符串，然后可以新建对应的派生类的实例，没啥难度，就是考察基本的知识。
class Shape {
public:
virtual void draw() const=;
};
class Rectangle: public Shape {
public:
void draw() const {
cout << " ---- " << endl;
cout << "| |" << endl;
cout << " ---- " << endl;
}
};
class Square: public Shape {
public:
void draw() const {
cout << " ---- " << endl;
cout << "| |" << endl;
cout << "| |" << endl;
cout << " ---- " << endl;
}
};
class Triangle: public Shape {
public:
void draw() const {
cout << " /\\ " << endl;
cout << " / \\ " << endl;
cout << "/____\\ " << endl;
}
};
class ShapeFactory {
public:
/**
* @param shapeType a string
* @return Get object of type Shape
*/
Shape* getShape(string& shapeType) {
if (shapeType == "Square") return new Square();
else if (shapeType == "Triangle") return new Triangle();
else if (shapeType == "Rectangle") return new Rectangle();
else return NULL;
}
};