设计模式（五）：工厂模式

  设计模式，是一种指导思想，是一种需要融合进代码设计的一种提纲挈领。

  今天进入工厂模式探究：

  简单工厂：

     简单工厂即在工厂类中，根据所输入产品的类型，生产对应的产品。但是，这样的话，工程类就需要包含所有产品的生产实现。例子如下：

    

#include <iostream>

using namespace std;


enum CAR_TYPE { 
    ROLLSROYCE,
    BENTLEY,
    MAYBACH,
    LAMBORGHINI,
    FERRARI,
    ASTONMARTIN
 };

class Car
{
public:
    Car(){}
    ~Car(){}

    virtual void showType(){}

    /* data */
};

class RollsRoyce : public Car
{
public:
    RollsRoyce(){}
    ~RollsRoyce(){}

    void showType()
    {
        cout << "Tish is RollsRoyce, from German." << endl;
    }
    /* data */
};

class Bentley : public Car
{
public:
    Bentley(){}
    ~Bentley(){}

    void showType()
    {
        cout << "This is Bentley, from England." << endl;
    }

    /* data */
};

class Maybach : public Car
{
public:
    Maybach(){}
    ~Maybach(){}

    /* data */
    void showType()
    {
        cout << "This is Maybach, from Netherland." << endl;
    }
};

class CarFactory
{
public:
    CarFactory(){}
    ~CarFactory(){}

    static Car* CreateFactory( enum CAR_TYPE carType )
    {
        if ( ROLLSROYCE == carType )
        {
            /* code */
            return new RollsRoyce();
        }
        else if ( BENTLEY == carType )
        {
            return new Bentley();
        }
        else if ( MAYBACH == carType )
        {
            return new Maybach();
        }
        else
        {
            return NULL;
        }
    }


    /* data */
};
    

void TestSimpleFactory()
{
    // CarFactory carfactory;

    Car* pCar = CarFactory::CreateFactory( ROLLSROYCE );
    pCar->showType();

    delete pCar;

    pCar = CarFactory::CreateFactory( BENTLEY );
    pCar->showType();

    delete pCar;
}

int main()
{
    TestSimpleFactory();
    return 0;
}

  上例中工厂类方法中，因为不涉及到其他的成员属性，所以使用static 类静态方法。

class Car(object):
    """docstring for Car"""
    def __init__(self):
        self.speed = None

class Rollsroyce( Car ):
    """docstring for """
    def __init__(self ):
        self.name = "Rollsroyce"

    def showType( self ):
        print "This is " + self.name

class Bentley( Car ):
    def __init__( self ):
        self.name = "Bentley"

    def showType( self ):
        print "This is " + self.name

class CarFactory(object):
    """docstring for CarFactory"""
    
    @classmethod
    def CreateCar( cls, type ):
        if "BENTLEY" == type:
            return Bentley()
        elif "ROLLSROYCE" == type:
            return Rollsroyce()


        

if __name__ == '__main__':
    car = CarFactory.CreateCar( "BENTLEY" )
    car.showType()
    car = CarFactory.CreateCar( "ROLLSROYCE" )
    car.showType()