C++로 Java와 동일한 로직을 구현해보자!

다음 Java 로직을 C++로 구현해 보자.

 

[Java]

// strategy.java
public interface Strategy {
        public int doOperation(int num1, int num2);
}

// OperationAdd.java
public class OperationAdd implements Strategy{
@Override
    public int doOperation(int num1, int num2) {
        return num1 + num2;
    }
}
// OperationSubstract.java
public class OperationSubstract implements Strategy{
    @Override
    public int doOperation(int num1, int num2) {
        return num1 - num2;
    }
}
// OperationMultiply.java
public class OperationMultiply implements Strategy{
@Override
    public int doOperation(int num1, int num2) {
        return num1 * num2;
    }
}
// Context.java
public class Context {
    private Strategy strategy;
    public Context(Strategy strategy){
            this.strategy = strategy;
        }
    public int executeStrategy(int num1, int num2){
            return strategy.doOperation(num1, num2);
        }
}
// StrategyPatternDemo.java
public class StrategyPatternDemo {
    public static void main(String[] args) {
            Context context = new Context(new OperationAdd());
            System.out.println("10 + 5 = " + context.executeStrategy(10, 5));
            context = new Context(new OperationSubstract());
            System.out.println("10 - 5 = " + context.executeStrategy(10, 5));
            context = new Context(new OperationMultiply());
            System.out.println("10 * 5 = " + context.executeStrategy(10, 5));
        }
}

 

 

 

[C++]

#include <iostream>
using namespace std;

class Strategy{
public:
    virtual int doOperation (int num1, int num2) = 0;
};

class OperationAdd : public Strategy{
public:
    int doOperation(int num1, int num2) override{
        return num1 + num2;
    }
};
class OperationSubstract : public Strategy{
public:
    int doOperation(int num1, int num2) override{
        return num1 - num2;
    }
};
class OperationMultiply : public Strategy{
public:
    int doOperation(int num1, int num2) override{
        return num1 * num2;
    }
};

class Context {
private:
    Strategy *strategy;
public:
    Context(Strategy *strategy){ this->strategy = strategy; }
    int executeStrategy(int num1, int num2) { return strategy->doOperation(num1, num2); }
};

int main(){
    Context *context = new Context(new OperationAdd);
    cout << "10 + 5 = " << context->executeStrategy(10, 5) << endl;

    context = new Context(new OperationSubstract());
    cout << "10 - 5 = " << context->executeStrategy(10, 5) << endl;

    context = new Context(new OperationMultiply());
    cout << "10 * 5 = " << context->executeStrategy(10, 5) << endl;
}

 

핵심 포인트!

1. private에 Strategy 클래스의 객체를 생성할 수 있다.

2. 생성자의 매개변수로 객체를 생성할 수 있다.

class Context {
private:
    Strategy *strategy;
public:
    Context(Strategy *strategy){ this->strategy = strategy; }
    int executeStrategy(int num1, int num2) { return strategy->doOperation(num1, num2); }
};