How to convert linq results to HashSet or HashedSet

Question

I have a property on a class that is an ISet. I\'m trying to get the results of a linq query into that property, but can\'t figure out how to do so.

Basically, look

Answer 1

Rather than the simple conversion of IEnumerable to a HashSet, it is often convenient to convert a property of another object into a HashSet. You could write this as:

var set = myObject.Select(o => o.Name).ToHashSet();

but, my preference would be to use selectors:

var set = myObject.ToHashSet(o => o.Name);

They do the same thing, and the the second is obviously shorter, but I find the idiom fits my brains better (I think of it as being like ToDictionary).

Here's the extension method to use, with support for custom comparers as a bonus.

public static HashSet ToHashSet(
    this IEnumerable source,
    Func selector,
    IEqualityComparer comparer = null)
{
    return new HashSet(source.Select(selector), comparer);
}