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Strategy Pattern

Strategy Pattern 


Gamma Categorization: Behavioral Design Pattern
Summary: Define a family of algorithms, encapsulate each one, and make them interchangeable. Strategy lets the algorithm vary independently from clients that use it.

Sample Code

Problem: We want to have a shooting strategies based on the photo conditions.

Code

public abstract class ShootingStrategy
{
    public abstract void TakePhoto();
}

public class LandscapeStrategy : ShootingStrategy
{
    public override void TakePhoto()
    {
        Console.WriteLine("Taking photo with low ISO and great focal distance.");
    }
}

public class SportsStrategy : ShootingStrategy
{
    public override void TakePhoto()
    {
        Console.WriteLine("Taking photo with high ISO and fast shutter speed.");
    }
}

public class ShootingMethod
{
    private ShootingStrategy _shootingStrategy;

    public void SetShootingStrategy(ShootingStrategy shootingStrategy)
    {
        this._shootingStrategy = shootingStrategy;
    }

    public void Shoot()
    {
        _shootingStrategy.TakePhoto();
    }
}

Usage

var shootingMethod = new ShootingMethod();

System.Console.WriteLine("\nSeaside photo with the camera on a tripod:");
shootingMethod.SetShootingStrategy(new LandscapeStrategy());
shootingMethod.Shoot();

System.Console.WriteLine("\nCyclism photo handholding the camera:");
shootingMethod.SetShootingStrategy(new SportsStrategy());
shootingMethod.Shoot();

Output

Seaside photo with the camera on a tripod:
Taking photo with low ISO and great focal distance.

Cyclism photo handholding the camera:
Taking photo with high ISO and fast shutter speed.


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