[디자인패턴] 전략패턴 (Strategy Pattern)

전략 패턴 간단한 예제

Class 구현부

namespace StrategyPattern
{
    class Context
    {
        private IStrategy IStrategy;
        public Context() { }

        public Context(IStrategy strategy)
        {
            IStrategy = strategy;
        }

        public void SetValue(IStrategy strategy)
        {
            IStrategy = strategy;
        }

        public void DoSomething()
        {
            Console.WriteLine("context DoSomething()");
            var test = IStrategy.algo(1);

        }
    }

    public interface IStrategy 
    {
        object algo(int data);
    }

    class Someobj1 : IStrategy
    { 
        public object algo(int data) 
        {
            Console.WriteLine($"this is someobj1 : {data}");
            return new object();
        }
    }
    class Someobj2 : IStrategy
    {
        public object algo(int data)
        {
            Console.WriteLine($"this is someobj2 : {data}");
            return new object();
        }
    }
}

Main

namespace StrategyPattern;
public class MainProject
{
    static void Main(string[] args)
    {
        var context = new Context();

        context.SetValue(new Someobj1());
        context.DoSomething();

        context.SetValue(new Someobj2());
        context.DoSomething();
    }
}

결과

context DoSomething()
this is someobj1 : 1
context DoSomething()
this is someobj2 : 1

---

또다른 예제

using System;
using System.Collections.Generic;

namespace StrategyPatternExample
{
    // 무기 클래스
    public class Weapon
    {
        private List<IElementalStrategy> elementalStrategies = new List<IElementalStrategy>();

        public void AddElementalStrategy(IElementalStrategy elementalStrategy)
        {
            elementalStrategies.Add(elementalStrategy);
        }

        public void Attack()
        {
            if (elementalStrategies.Count == 0)
            {
                Console.WriteLine("Attacking with a standard weapon.");
            }
            else
            {
                Console.Write("Attacking with a weapon that has the following elements: ");
                foreach (var strategy in elementalStrategies)
                {
                    Console.Write(strategy.GetElementalType() + " ");
                }
                Console.WriteLine();
            }
        }
    }

    // 속성 전략 인터페이스
    public interface IElementalStrategy
    {
        string GetElementalType();
    }

    // 물속성 전략
    public class WaterElementalStrategy : IElementalStrategy
    {
        public string GetElementalType()
        {
            return "Water";
        }
    }

    // 독속성 전략
    public class PoisonElementalStrategy : IElementalStrategy
    {
        public string GetElementalType()
        {
            return "Poison";
        }
    }

    // 불속성 전략
    public class FireElementalStrategy : IElementalStrategy
    {
        public string GetElementalType()
        {
            return "Fire";
        }
    }

    // 흙속성 전략
    public class EarthElementalStrategy : IElementalStrategy
    {
        public string GetElementalType()
        {
            return "Earth";
        }
    }

    class Program
    {
        static void Main(string[] args)
        {
            var weapon = new Weapon();

            // 두 개 이상의 속성을 가진 무기를 만듭니다.
            weapon.AddElementalStrategy(new WaterElementalStrategy());
            weapon.AddElementalStrategy(new FireElementalStrategy());
            weapon.Attack();

            // 세 개의 속성을 가진 무기로 변경합니다.
            weapon.AddElementalStrategy(new EarthElementalStrategy());
            weapon.Attack();
        }
    }
}