#541 – Generic Method Type Parameters Can Hide Class-Level Type Parameters

When you have generic methods within a generic class, if the name of a type parameter in the generic method matches the name of a type parameter for the class, the parameter in the method takes precedence.

In the example below, both the Dog class and the BuryThing method declare a type parameter named T.  Within the body of the BuryThing method, the method’s type parameter is used, rather than the class-level type parameter of the same name.

    public class Dog<T>
    {
        // This method's type parameter hides the class-level type parameter
        public void BuryThing<T>(T thing)
        {
            Console.WriteLine("T's type is {0}", typeof(T).ToString());
        }

 

            Dog<Cow> d = new Dog<Cow>("Buster", 5);
            d.BuryThing(new Bone("Rawhide"));

To avoid this confusion, you should give your type parameters meaningful names, e.g. TDogThing and TThingToBury.

Advertisements