Why is generic constructor not allowed?

  • Article

Generic argument is not allowed in the constructor. When I compile the code below I get a compilation error saying:

error CS1519: Invalid token '(' in class, struct, or interface

        member declaration

The reason is simple. You can have a class Foo<T> and a class Foo as described in my previous post. Now when you says

fooInstance = new Foo<T>();

there is no way for the compiler to find out the right class constructor to call.

namespace Sample

{

    using System;

    public class Foo <T>

    {

    }

    class Foo

    {

        public Foo<T>()

        {

            Console.WriteLine("This is generic Foo class {0}",typeof(T));

        }

    }

    public class Bar

    {

        static public void Main()

        {

            Foo fooGenericInstance;

            fooGenericInstance = new Foo<Int32>();

        }

    }

}