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How are generics implemented for value types vs reference types in the CLR? What problem do generic math / static abstract interface members solve? How would you implement a generic method with MULTIPLE type parameters and constraints that reference EACH OTHER, like a generic mapping function? How do generic type parameters interact with static members, and why does each closed generic type get its OWN independent set of static field values? How do generic attributes (introduced in C# 11) work, and what limitation did they finally remove compared to older attribute usage patterns? How would you implement generic operator constraints using .NET's generic math interfaces (like INumber<T>) to write a single Sum<T>() method working across int, double, and decimal?
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How would you implement a generic, reusable object pool using generic constraints to ensure poolable objects can be properly reset?

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Answer

Constrain the pool's type parameter to an interface (like IPoolable) requiring a Reset() method, letting the generic pool safely call it when returning an object to the pool — this avoids unsafe casting or reflection while keeping the pool fully generic and reusable across any poolable type.
public interface IPoolable { void Reset(); }

public class ObjectPool<T> where T : class, IPoolable, new() {
  private readonly Stack<T> _pool = new();
  public T Rent() => _pool.Count > 0 ? _pool.Pop() : new T();
  public void Return(T item) { item.Reset(); _pool.Push(item); }
}
Real-world example Building a reusable pool for expensive-to-create objects (like StringBuilder or a game entity) to reduce garbage collection pressure in a hot loop.

Common follow-ups: How does this hand-rolled pool compare to the built-in Microsoft.Extensions.ObjectPool library's ObjectPool<T>?

Memory & Garbage Collection
All 17 Generics questions