#1,037 – Specifying Type Parameter Constraints for More than One Type Parameter

If you define a generic type that includes more than one type parameter, you can specify type parameter constraints for each parameter independently.

In the example below, we define a generic class that accepts two type parameters.  We specify that the first type must be one that implements the IMoo interface and that the second type must implement IBark.

    public class MooBarkPile<T1,T2> where T1 : IMoo
                                   where T2 : IBark
    {
        private List<T1> mooPile = new List<T1>();
        private List<T2> barkPile = new List<T2>();

        public void AddMooThing(T1 thing)
        {
            mooPile.Add(thing);
            mooPile[mooPile.Count - 1].Moo();
        }

        public void AddBarkThing(T2 thing)
        {
            barkPile.Add(thing);
            barkPile[barkPile.Count - 1].Bark("Woof");
        }
    }

We can now use the type as follows:

            MooBarkPile<Cow,Dog> aPile = new MooBarkPile<Cow,Dog>();
            aPile.AddBarkThing(new Dog("Kirby", 10));
            aPile.AddMooThing(new Cow("Bessie"));