gistfile1.cs

public class Tools
{
    public int Add(int a, int b)
    {
        return a + b;
    }

    public void Log<T>(T param)
    {
        Console.WriteLine($"{param}");
    }

    public T FindMax<T>(T a, T b)
        where T : IComparable
    {
        // if (a > b) // ?! nem értelmezhető --> megszorítás
        return a.CompareTo(b) > 0 ? a : b;
    }

    public bool CompareByValue<T, K>(T valueA, K valueB)
    {
        return valueA.Equals(valueB);
    }

    public bool CompareByType<T, K>()
    {
        return typeof(T).Equals(typeof(K));
    }
}

public class Box<T>
{
    public T Value { get; set; }

    public Box(T value)
    {
        this.Value = value;
    }

    public Box() { }

    public override string ToString()
    {
        return $"Box({Value})";
    }
}

public class CardboardBox<T, Z> : Box<string> { }

public class MisteryBox<T, Z> : Box<T>
{
    // public MisteryBox(T value) : base(value)
    // {
    // }
}

public class Pair<K, V>
    where K : IComparable
    where V : class
{
    public K Key { get; set; }
    public V Value { get; set; }

    public Pair(K key, V value)
    {
        this.Key = key;
        this.Value = value;
    }
}

public class ObjectFactory<T>
    where T : new()
{
    public List<T> Create(int number)
    {
        List<T> list = new List<T>();
        for (int i = 0; i < number; i++)
        {
            list.Add(new T());
        }
        return list;
    }
}

internal class Program
{
    private static void Main(string[] args)
    {
        var tools = new Tools();
        tools.Log("alma");
        tools.Log(123);

        tools.Log<string>("alma");
        tools.Log<int>(123);

        var box = new Box<string>("this is my box");
        var pair = new Pair<int, Box<string>>(10, box);

        var of = new ObjectFactory<Box<string>>();
        var items = of.Create(4);
        ;
    }
}