迪米特法則 又叫最少知識法則

類中的成員屬性和成員方法，如果不需要對外暴露，就不要設成public。

代碼如下:

#include <iostream> #include <string> using namespace std;class AbstractBuilding { public:virtual void sale() = 0; };class BuildingA :public AbstractBuilding { public:BuildingA():quilty("高品質"){}virtual void sale(){cout << "樓盤A" << quilty << "被售賣!" << endl;}string quilty; };class BuildingB :public AbstractBuilding { public:BuildingB() :quilty("低品質") {}virtual void sale(){cout << "樓盤B" << quilty << "被售賣!" << endl;}string quilty; };void test01() {BuildingA *ba = new BuildingA;if (ba->quilty == "低品質"){ba->sale();}BuildingB *bb = new BuildingB;if (bb->quilty == "低品質"){bb->sale();} }int main() {test01();return 0; }

測試結果:

迪米特法則
代碼如下:

#include <iostream> #include <string> #include <vector> using namespace std;class AbstractBuilding { public:virtual void sale() = 0;virtual string getQuilty() = 0; };class BuildingA :public AbstractBuilding { public:BuildingA():quilty("高品質"){}virtual void sale(){cout << "樓盤A" << quilty << "被售賣!" << endl;}virtual string getQuilty(){return quilty;} private:string quilty; };class BuildingB :public AbstractBuilding { public:BuildingB() :quilty("低品質") {}virtual void sale(){cout << "樓盤B" << quilty << "被售賣!" << endl;}virtual string getQuilty(){return quilty;}private:string quilty; };//中介類 class Mediator { public:Mediator(){AbstractBuilding *building = new BuildingA;vBuilding.push_back(building);building = new BuildingB;vBuilding.push_back(building);}~Mediator(){for (vector<AbstractBuilding*>::iterator it = vBuilding.begin(); it != vBuilding.end(); it++){if (*it != nullptr){delete *it;}}}//對外提供接口AbstractBuilding *findMyBuilding(string quality){for (vector<AbstractBuilding*>::iterator it = vBuilding.begin(); it != vBuilding.end(); it++){if ((*it)->getQuilty()==quality){return *it;}}return nullptr;}vector<AbstractBuilding*> vBuilding;};void test01() {Mediator *mediator = new Mediator;//優點:用戶不用跟具體樓盤打交道AbstractBuilding * building = mediator->findMyBuilding("高品質");if (building != nullptr){building->sale();}else{cout << "沒有符合條件的樓盤" << endl;} }int main() {test01();return 0; }

測試結果:

總結

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