This appears to be a typo, in both the downloadable sample code, and on page 51. The code in the ctor should test for inequality.

public class MySampleClass<T> {
    private static List<T> _values;

    static MySampleClass() {
        if (typeof(T).IsAbstract == false)
            throw new Exception("T must not be abstract");
        else
            _values = new List<T>();
    }
}


Ketil Wright

I came here to look at the errata when I saw that too. I was hoping it wasn't just me.

I typed "if (typeof(T).IsAbstract == true)" in my C# instead of "if (typeof(T).IsAbstract == false)" and it worked fine.
A similar issue is already mentioned in the Errata for the VB code.

I tried using the Errata Form to report the problem in C# but the form was asking me for some password so I gave up