Should overloaded methods with value types be consolidated into a generic method ?

Question

Hi,

When performing OO design, is it better to consolidate a collection of methods that use simple value types into a generic method ? For example:

public int Sum(int x, int y)

// Overload with float.
public float Sum(float x, float y)

Consolidated to:

public T Sum<T> (T x, T y)

Thanks,

Scott

Answer 1

In general yes, however, specifically with your example (summing two arguments) - you can't do it with generics, since the + operator is not part of any interface to which you can constrain your generic type argument :)

(Note: this is my C# part talking, in other languages that might still be possible)

Answer 2

In some cases, yes (not always); and despite rumour to the contrary, it is possible. I wrote some code for "MiscUtil" (free, etc) that does exactly this, and which works for all types with suitable operators (even your own structs and classes, or Nullable<T>, etc).

The problem here is that there is no interface that supports Add etc, so until dynamic comes along (in 4.0) it is tricky to do; but it can be done - here's the usage page, with a simiplfied Sum (the actual code in "MiscUtil" is slightly more complex):

public static T Sum<T>(this IEnumerable<T> source)
{
    T sum = Operator<T>.Zero;
    foreach (T value in source)
    {
        if (value != null)
        {
            sum = Operator.Add(sum, value);
        }
    }
    return sum;
}

Again, a lot of this is relatively simple in 4.0 with dynamic, since this supports operators; however, last time I benchmarked it, dynamic was slower than my (ab)use of Expression.

As an aside, the reason that standard LINQ can provide a Min / Max is because of IComparable/IComparable<T>, assisted by Comparer<T>.Default.