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.