IEnumerable Extension Methods on an Enum

问题

I have an enum(below) that I want to be able to use a LINQ extension method on.

enum Suit{
    Hearts = 0,
    Diamonds = 1,
    Clubs = 2,
    Spades = 3
}

Enum.GetValues(...) is of return type System.Array, but I can't seem to get access to a ToList() extension or anything else of that sort.

I'm just looking to write something like...

foreach(Suit s in Enum.GetValues(typeof(Suit)).Select(x=>x).Where(x=> x != param)){}

Is there something I'm missing, or can someone explain to me why this isn't possible?

Thanks.

回答1:

Enum.GetValues returns a System.Array and System.Array only implements IEnumerable rather than IEnumerable<T> so you will need to use the Enumerable.OfType extension method to convert the IEnumerable to IEnumerable<Suit> like this:

Enum.GetValues(typeof(Suit))
            .OfType<Suit>()
            .Where(x => x != param);

Edit: I removed the call to IEnumerable.Select as it was a superfluous projection without any meaningful translation. You can freely filter the IEnumerable<Suit> that is returned from OfType<T>.

回答2:

Array implements IEnumerable so you'll need to use Cast<Suit> or OfType<Suit> to get the IEnumerble<T> extensions like ToList();

来源：https://stackoverflow.com/questions/1752194/ienumerable-extension-methods-on-an-enum