C#: Use Generics for Type-Safe and Reusable Code – Bits of .NET

C#

C#: Use Generics for Type-Safe and Reusable Code

- 24.06.26 - ErcanOPAK

📦 Generics = Type-Safe Reusable Code

Object types lose type safety. Generics preserve types. Reusable code, compile-time safety, no casting.

❌ Without Generics

public class List
{
    private object[] _items;
    public void Add(object item) { }
    public object Get(int index) { }
}
// Boxed int, cast required

✅ With Generics

public class List
{
    private T[] _items;
    public void Add(T item) { }
    public T Get(int index) { }
}
// Type-safe, no casting

🎯 Generic Methods and Constraints

// Generic method
public T GetDefault() where T : new()
{
    return new T();
}

// Generic class with constraint
public class Repository where T : class, new()
{
    private List _items = new List();
    
    public void Add(T item) => _items.Add(item);
    public T GetFirst() => _items.FirstOrDefault();
}

// Multiple constraints
public class Service where T : class, IDisposable, new()
{
    // T must be class, implement IDisposable, have default constructor
}

// Covariance and Contravariance
IEnumerable