Strategy

Strategy ist ein verhaltensorientiertes Entwurfsmuster, mit dem du eine Familie von Algorithmen definierst, jeden von ihnen in einer eigenen Klasse unterbringst und ihre Objekte austauschbar machen kannst.

Klassendiagramm

Implementierung

Context

Context.cs

public class Context
{
    private Strategy? _strategy;

    public void SetStrategy(Strategy strategy)
    {
        _strategy = strategy;
    }

    public void ExecuteStrategy()
    {
        _strategy?.Execute();
    }
}

IStrategy

IStrategy.cs

public interface Strategy
{
    void Execute();
}

ConcreteStrategyA

ConcreteStrategyA.cs

public class ConcreteStrategyA : Strategy
{
    public void Execute()
    {
        Console.WriteLine("Executing strategy A");
    }
}

ConcreteStrategyB

ConcreteStrategyB.cs

public class ConcreteStrategyB : Strategy
{
    public void Execute()
    {
        Console.WriteLine("Executing strategy B");
    }
}

ConcreteStrategyC

ConcreteStrategyC.cs

public class ConcreteStrategyC : Strategy
{
    public void Execute()
    {
        Console.WriteLine("Executing strategy C");
    }
}

Beispiel

Klassendiagramm

Implementierung

Context

ShoppingCart.cs

public class ShoppingCart
{
    private IPaymentStrategy? _strategy;

    public void SetStrategy(IPaymentStrategy strategy)
    {
        _strategy = strategy;
    }

    public void Checkout(decimal amount)
    {
        _strategy?.Pay(amount);
    }
}

IStrategy

IPaymentStrategy.cs

public interface IPaymentStrategy
{
    void Pay(decimal amount);
}

ConcreteStrategyA

CreditCardStrategy.cs

public class CreditCardStrategy(
    string name,
    string cardNumber,
    string cvv,
    string dateOfExpiry) : IPaymentStrategy
{
    private string _name = name;
    private string _cardNumber = cardNumber;
    private string _cvv = cvv;
    private string _dateOfExpiry = dateOfExpiry;

    public void Pay(decimal amount)
    {
        Console.WriteLine($"Paid {amount} using credit card");
    }
}

ConcreteStrategyB

BankTransferStrategy.cs

public class BankTransferStrategy(string bankName, string accountNumber) : IPaymentStrategy
{
    private readonly string _bankName = bankName;
    private readonly string _accountNumber = accountNumber;

    public void Pay(decimal amount)
    {
        Console.WriteLine($"Paid {amount} using Bank Transfer");
    }
}

ConcreteStrategyC

PayPalStrategy.cs

public class PayPalStrategy(string email, string password) : IPaymentStrategy
{
    private string _email = email;
    private string _password = password;

    public void Pay(decimal amount)
    {
        Console.WriteLine($"Paid {amount} using PayPal");
    }
}