Question

My code is simply:

  public override C Calculator<C>(Team[] teams, Func<Team, C> calculatorFunc)
    {
        return teams.Average(calculatorFunc);
    }     

I get this error:

Error 2 The type arguments for method ‘System.Linq.Enumerable.Average(System.Collections.Generic.IEnumerable, System.Func)’ cannot be inferred from the usage. Try specifying the type arguments explicitly.

How can I fix this?

Answer 1

You can’t – at least in the current form. There is no Average overload available that works on completely generic values (i.e. for all types C as you specified).

Average needs lists of numbers (int, double, float …) or a conversion function that produces numbers. In the current form, you could call Calculator<string> and it would make absolutely no sense to compute the average of strings.

You’ll just have to restrict the method to a specific numeric type (or provide overloads), but generics simply won’t work.