学习笔记：享元模式

考虑一个表

student

ID	name	city	province	country	...	...
1	A
2	B
3	C
4	D
5	E

根据数据库设计范式，里面有冗余数据。应改进为：

student

ID	name	city	...	...	...	...
1	A	New York
2	B	New York
3	C	Beijing
4	D	Beijing
5	E	Beijing

city

city	province	country
New York	...	...
Beijing	...	...
Paris	...	...
...	...	...

在程序设计语言中，这个技术被称为设计模式之享元模式

class Student{
public:
    string id;
    string name;
    int city_idx;
    string getCountry();
    string getProvince();
    string getCity();
};

string Student::getCountry(){
    return CityFlyWeightFactory::getCountry(city_idx);
}