Bounded Generic Types in Method Parameters C#

Question

Question: Does C# support bounded generic types in method parameters? If so what is the syntax?

Context: I am writing a utility method that sorts a Dictionary on the values within the dictionary. Therefore the values in the Dictionary must implement the IComparable interface.

Attempt(s): The code below takes a Dictionary, get the list of KeyValuePair, sorts on the Value and then returns the top keys in the dictionary as reported by their values.

private string[] getTopWords<T , U>(Dictionary<T, U> similarWordsAndWeights)
{
    var myList = similarWordsAndWeights.ToList();

    myList.Sort((firstPair, nextPair) =>
    {
        return -firstPair.Value.CompareTo(nextPair.Value);
    }
    );
    var dictionary = myList.ToDictionary((keyItem) => keyItem.Key, (valueItem) => valueItem.Value);
    return createStringArrayFromGenericList(dictionary.Keys.ToList().GetRange(0, 10));
}

However this code will not compile as U is not "guaranteed" to implement IComparable. The syntax private string[] getTopWords<T, U : IComparable> will also not compile.

I could type check to see that my U implements IComparable however I would rather not.

Answer 1

So shortly after going through writing my question I looked on MSDN and found an article on generics which I had been through already however halfway down the page I found the answer that I was looking for. Here is the code for the solution:

private string[] getTopWords<T , U>(Dictionary<T, U> similarWordsAndWeights) where U : IComparable
{
    var myList = similarWordsAndWeights.ToList();

    myList.Sort((firstPair, nextPair) =>
    {
        return -firstPair.Value.CompareTo(nextPair.Value);
    }
    );
    var dictionary = myList.ToDictionary((keyItem) => keyItem.Key, (valueItem) => valueItem.Value);
    return createStringArrayFromGenericList(dictionary.Keys.ToList().GetRange(0, NUMBER_OF_WORDS_TO_RETURN));
}

It appears that you do the bounding declaration AFTER the parameters. I was looking for something before (having a Java background) and of course was not able to find anything. Amazing what one can do on google with just a few extra minutes...

I thought it wise to share my solution as I was not able to find anything specifically on SO and it may be helpful to others that end up searching for the same thing.